tcp: Fix data-races around sysctl_tcp_mtu_probing.

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


Upstream Status: linux.git

commit f47d00e0
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date:   Wed Jul 13 13:52:00 2022 -0700

    tcp: Fix data-races around sysctl_tcp_mtu_probing.

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

    Fixes: 5d424d5a ("[TCP]: MTU probing")
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>