net: add missing READ_ONCE(sk->sk_sndbuf) annotation

stable inclusion
from stable-v5.10.190
commit dc20f7bada00b550b3fd2855ec910a33460ed357
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I928UI

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dc20f7bada00b550b3fd2855ec910a33460ed357



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[ Upstream commit 74bc0843 ]

In a prior commit, I forgot to change sk_getsockopt()
when reading sk->sk_sndbuf locklessly.

Fixes: e292f05e ("tcp: annotate sk->sk_sndbuf lockless reads")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>