net: annotate data-races around sk->sk_priority

sk_getsockopt() runs locklessly. This means sk->sk_priority
can be read while other threads are changing its value.

Other reads also happen without socket lock being held.

Add missing annotations where needed.

Fixes: 1da177e4

 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>