tcp: remove READ_ONCE(req->ts_recent)

tcp: remove READ_ONCE(req->ts_recent)

After commit 8d52da23b6c6 ("tcp: Defer ts_recent changes
until req is owned"), req->ts_recent is not changed anymore.

It is set once in tcp_openreq_init(), bpf_sk_assign_tcp_reqsk()
or cookie_tcp_reqsk_alloc() before the req can be seen by other
cpus/threads.

This completes the revert of eba20811f326 ("tcp: annotate
data-races around tcp_rsk(req)->ts_recent").

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Wang Hai <wanghai38@huawei.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250301201424.2046477-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>