tcp: avoid atomic operations on sk->sk_rmem_alloc

TCP uses generic skb_set_owner_r() and sock_rfree()
for received packets, with socket lock being owned.

Switch to private versions, avoiding two atomic operations
per packet.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250320121604.3342831-1-edumazet@google.com


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