tcp: annotate data-races around icsk->icsk_pending

tcp: annotate data-races around icsk->icsk_pending

icsk->icsk_pending can be read locklessly already.

Following patch in the series will add another lockless read.

Add smp_load_acquire() and smp_store_release() annotations
because following patch will add a test in tcp_write_timer(),
and READ_ONCE()/WRITE_ONCE() alone would possibly lead to races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241002173042.917928-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>