af_unix: Add missing annotation for unix_wait_for_peer()

Sparse reports a warning unix_wait_for_peer()

warning: context imbalance in unix_wait_for_peer() - unexpected unlock

The root cause is the missing annotation at unix_wait_for_peer()
Add the missing annotation __releases(&unix_sk(other)->lock)

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/unix/af_unix.c

@@ -1207,6 +1207,7 @@ out:
 }
 
 static long unix_wait_for_peer(struct sock *other, long timeo)
+	__releases(&unix_sk(other)->lock)
 {
 	struct unix_sock *u = unix_sk(other);
 	int sched;