Small refactor and cleanup into helper functions. Also when we test
whether the key is a wildcard key, really test for port and proto to
make sure we otherwise never can hit this.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

For the case of E/W, do not perform a wildcarded/fallback lookup. This
seems to break a couple of cases:

- socket LB's bind detection could break if an application binds
  to the same VIP, and we return with a svc in __sock{4,6}_post_bind().

- In the sendto/connect case when a service lookup fails, we perform
  sock{4,6}_wildcard_lookup() with a 0.0.0.0 wildcard address as VIP
  (not the same "wildcard" concept as the former). This fallback lookup
  is mainly for NodePort to access a service under loopback or any
  local address. We don't know a-priori whether we are going to need
  this lookup. It could happen that we never end up doing the 0.0.0.0
  lookup if we return a service via lb{4,6}_key_is_wildcard().

Given this incompatibility, disable it when east_west is true and just
return NULL as we did before.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>