sctp: Add missing annotation for sctp_transport_walk_stop()

Sparse reports a warning at sctp_transport_walk_stop()

warning: context imbalance in sctp_transport_walk_stop
	- wrong count at exit

The root cause is the missing annotation at sctp_transport_walk_stop()
Add the missing __releases(RCU) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -5340,7 +5340,7 @@ void sctp_transport_walk_start(struct rhashtable_iter *iter) __acquires(RCU)
 	rhashtable_walk_start(iter);
 }
 
-void sctp_transport_walk_stop(struct rhashtable_iter *iter)
+void sctp_transport_walk_stop(struct rhashtable_iter *iter) __releases(RCU)
 {
 	rhashtable_walk_stop(iter);
 	rhashtable_walk_exit(iter);