tcp: Remove inet6_hash().

inet_hash() and inet6_hash() are exactly the same.

Also, we do not need to export inet6_hash().

Let's consolidate the two into __inet_hash() and rename it to inet_hash().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250919083706.1863217-3-kuniyu@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>