tcp: adopt try_cmpxchg() in tcp_release_cb()

try_cmpxchg() is slighly more efficient (at least on x86),
and smp_load_acquire(&sk->sk_tsq_flags) could avoid a KCSAN report.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20221110174829.3403442-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>