[NET]: Add some acquires/releases sparse annotations.

Add __acquires() and __releases() annotations to suppress some sparse
warnings.

example of warnings :

net/ipv4/udp.c:1555:14: warning: context imbalance in 'udp_seq_start' - wrong
count at exit
net/ipv4/udp.c:1571:13: warning: context imbalance in 'udp_seq_stop' -
unexpected unlock

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/inet_hashtables.c

@@ -96,6 +96,7 @@ EXPORT_SYMBOL(inet_put_port);
  * exclusive lock release). It should be ifdefed really.
  */
 void inet_listen_wlock(struct inet_hashinfo *hashinfo)
+	__acquires(hashinfo->lhash_lock)
 {
 	write_lock(&hashinfo->lhash_lock);