tcp: Fix data-races around sysctl_tcp_ecn.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949


Upstream Status: linux.git

commit 4785a667
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date:   Mon Jul 11 17:15:30 2022 -0700

    tcp: Fix data-races around sysctl_tcp_ecn.

    While reading sysctl_tcp_ecn, it can be changed concurrently.
    Thus, we need to add READ_ONCE() to its readers.

    Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Guillaume Nault <gnault@redhat.com>