tcp: Save address type in inet_bind2_bucket.

inet_bind2_bucket_addr_match() and inet_bind2_bucket_match_addr_any()
are called for each bhash2 bucket to check conflicts.  Thus, we call
ipv6_addr_any() and ipv6_addr_v4mapped() over and over during bind().

Let's avoid calling them by saving the address type in inet_bind2_bucket.

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