ESP32-S2: cannot lightsleep again after a wakeup from ULP (IDFGH-4396)

## Environment

- Development Kit:      none
- Module or chip used:  ESP32-S2-WROOM
- IDF version: v4.3-dev-1901-g178b122c1
- Build System:         idf.py
- Compiler version: xtensa-esp32-elf-gcc (crosstool-NG esp-2020r3) 8.4.0
- Operating System:     macOS
- Using an IDE?:  No
- Power Supply:         external 3.3V

## Problem Description

On the ESP32-S2, I start the ULP RISC-V with an infinite loop calling `ulp_riscv_wakeup_main_processor()` at around 1 Hz.

On the main CPU I configure the ULP as the only wakeup source then I enter lightsleep.

Around 1 second after, the main CPU is awoken as expected.

Then I re-enter lightsleep, but this time the lightsleep exits instantly. (Before any wakeup call from the ULP).

### Expected Behavior

The ESP32-S2 should enter lightsleep a second time, and exit a second time ~1 second later (when the ULP sends the wakeup signal).

### Actual Behavior

After a first successful lightsleep / resume, every subsequent lightsleep exits instantly.

### Steps to reproduce

Compile, flash and run the following code:

### Code to reproduce this issue

main.c
```cpp
#include <stdio.h>
#include <esp_sleep.h>
#include <esp32s2/ulp_riscv.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <esp_rom_uart.h>

#include "ulp_main.h"

extern const uint8_t ulp_main_bin_start[] asm("_binary_ulp_main_bin_start");
extern const uint8_t ulp_main_bin_end[]   asm("_binary_ulp_main_bin_end");

void app_main(void)
{
    ESP_ERROR_CHECK(ulp_riscv_load_binary(ulp_main_bin_start, (ulp_main_bin_end - ulp_main_bin_start)));
    ESP_ERROR_CHECK(esp_sleep_enable_ulp_wakeup());
    ESP_ERROR_CHECK(ulp_riscv_run());
    
    while (true) {
        printf("ulp_n = %u ulp_n_wakeup = %u\n", ulp_n, ulp_n_wakeup);
        printf("Entering lightsleep\n");

        uint64_t t1 = esp_timer_get_time();
        esp_rom_uart_tx_wait_idle(0);
        esp_light_sleep_start();

        uint64_t t2 = esp_timer_get_time();
        esp_sleep_wakeup_cause_t reason = esp_sleep_get_wakeup_cause();
        printf("\nLightsleep exited, reason=%d, sleep_duration=%llu\n", reason, t2-t1);
        vTaskDelay(10);
    }
}
```

ulp/ulp.c
```cpp
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include "ulp_riscv/ulp_riscv.h"
#include "ulp_riscv/ulp_riscv_utils.h"

volatile int n = 0;
volatile int n_wakeup = 0;

int main(void)
{
    bool on = false;
    while (true) {
        n++;

        if (n % 100000 == 0) {
            n_wakeup++;
            ulp_riscv_wakeup_main_processor();
        }
    }
    return 0;
}
```

CMakeLists.txt
```
set(COMPONENT_SRCS "main.c")
set(COMPONENT_ADD_INCLUDEDIRS "")
set(COMPONENT_REQUIRES soc nvs_flash ulp driver)

register_component()

set(ulp_app_name ulp_${COMPONENT_NAME})
set(ulp_riscv_sources "ulp/ulp.c")
set(ulp_exp_dep_srcs "main.c")
ulp_embed_binary(${ulp_app_name} "${ulp_riscv_sources}" "${ulp_exp_dep_srcs}")
```

sdkconfig.defaults
```
# Enable ULP
CONFIG_ESP32S2_ULP_COPROC_ENABLED=y
CONFIG_ESP32S2_ULP_COPROC_RISCV=y
CONFIG_ESP32S2_ULP_COPROC_RESERVE_MEM=4096
```

## Debug Logs

```
ESP-ROM:esp32s2-rc4-20191025
Build:Oct 25 2019
rst:0x1 (POWERON),boot:0x8 (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:1
load:0x3ffe6100,len:0x8
load:0x3ffe6108,len:0x1818
load:0x4004c000,len:0x9d8
load:0x40050000,len:0x2e34
entry 0x4004c1ec
I (46) boot: ESP-IDF v4.3-dev-1901-g178b122c1 2nd stage bootloader
I (46) boot: compile time 16:18:47
I (46) boot: chip revision: 0
I (49) boot.esp32s2: SPI Speed      : 80MHz
I (54) boot.esp32s2: SPI Mode       : DIO
I (59) boot.esp32s2: SPI Flash Size : 2MB
I (63) boot: Enabling RNG early entropy source...
I (69) boot: Partition Table:
I (72) boot: ## Label            Usage          Type ST Offset   Length
I (80) boot:  0 nvs              WiFi data        01 02 00009000 00006000
I (87) boot:  1 phy_init         RF data          01 01 0000f000 00001000
I (94) boot:  2 factory          factory app      00 00 00010000 00100000
I (102) boot: End of partition table
I (106) esp_image: segment 0: paddr=0x00010020 vaddr=0x3f000020 size=0x06080 ( 24704) map
I (120) esp_image: segment 1: paddr=0x000160a8 vaddr=0x3ffbd480 size=0x025c8 (  9672) load
I (126) esp_image: segment 2: paddr=0x00018678 vaddr=0x40022000 size=0x00404 (  1028) load
I (133) esp_image: segment 3: paddr=0x00018a84 vaddr=0x40022404 size=0x07594 ( 30100) load
I (150) esp_image: segment 4: paddr=0x00020020 vaddr=0x40080020 size=0x112f4 ( 70388) map
I (165) esp_image: segment 5: paddr=0x0003131c vaddr=0x40029998 size=0x03adc ( 15068) load
I (176) boot: Loaded app from partition at offset 0x10000
I (176) boot: Disabling RNG early entropy source...
I (188) cache: Instruction cache 	: size 8KB, 4Ways, cache line size 32Byte
I (188) cpu_start: Pro cpu up.
I (242) cpu_start: Pro cpu start user code
I (242) cpu_start: cpu freq: 160000000
I (242) cpu_start: Application information:
I (245) cpu_start: Project name:     ulp-test
I (250) cpu_start: App version:      1
I (254) cpu_start: Compile time:     Dec  8 2020 16:18:42
I (260) cpu_start: ELF file SHA256:  fdcd4fb193f8d17d...
I (266) cpu_start: ESP-IDF:          v4.3-dev-1901-g178b122c1
I (273) heap_init: Initializing. RAM available for dynamic allocation:
I (280) heap_init: At 3FF9E000 len 00002000 (8 KiB): RTCRAM
I (286) heap_init: At 3FFC01D8 len 0003BE28 (239 KiB): DRAM
I (292) heap_init: At 3FFFC000 len 00003A10 (14 KiB): DRAM
I (299) spi_flash: detected chip: generic
I (303) spi_flash: flash io: dio
W (307) spi_flash: Detected size(4096k) larger than the size in the binary image header(2048k). Using the size in the binary image header.
I (321) cpu_start: Starting scheduler on PRO CPU.
ulp_n = 0 ulp_n_wakeup = 0
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=998509
ulp_n = 109574 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6038
ulp_n = 119702 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6040
ulp_n = 129830 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6038
ulp_n = 139958 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6040
ulp_n = 150087 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6039
ulp_n = 160215 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6052
ulp_n = 170344 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6039
ulp_n = 180470 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6040
ulp_n = 190598 ulp_n_wakeup = 1
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6039
ulp_n = 200725 ulp_n_wakeup = 2
Entering lightsleep

Lightsleep exited, reason=6, sleep_duration=6041
ulp_n = 210852 ulp_n_wakeup = 2
Entering lightsleep
```



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ESP32-S2: cannot lightsleep again after a wakeup from ULP (IDFGH-4396) #6229

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ESP32-S2: cannot lightsleep again after a wakeup from ULP (IDFGH-4396) #6229

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