tcp: annotate data-races around icsk->icsk_syn_retries

do_tcp_getsockopt() and reqsk_timer_handler() read
icsk->icsk_syn_retries while another cpu might change its value.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-7-edumazet@google.com


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