tcp: Factorise sk_family-independent comparison in inet_bind2_bucket_match(_addr_any).

This is a prep patch to make the following patches cleaner that touch
inet_bind2_bucket_match() and inet_bind2_bucket_match_addr_any().

Both functions have duplicated comparison for netns, port, and l3mdev.
Let's factorise them.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>