tcp: add tcp_release_cb_cond() helper

tcp: add tcp_release_cb_cond() helper

Majority of tcp_release_cb() calls do nothing at all.

Provide tcp_release_cb_cond() helper so that release_sock()
can avoid these calls.

Also hint the compiler that __release_sock() and wake_up()
are rarely called.

$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-77 (-77)
Function                                     old     new   delta
release_sock                                 258     181     -77
Total: Before=25235790, After=25235713, chg -0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260310124451.2280968-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>