[NET]: Transform skb_queue_len() binary tests into skb_queue_empty()

This is part of the grand scheme to eliminate the qlen
member of skb_queue_head, and subsequently remove the
'list' member of sk_buff.

Most users of skb_queue_len() want to know if the queue is
empty or not, and that's trivially done with skb_queue_empty()
which doesn't use the skb_queue_head->qlen member and instead
uses the queue list emptyness as the test.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index fc456a7..3405fdf 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -858,7 +858,7 @@
 {
 	struct netlink_sock *nlk = nlk_sk(sk);
 
-	if (!skb_queue_len(&sk->sk_receive_queue))
+	if (skb_queue_empty(&sk->sk_receive_queue))
 		clear_bit(0, &nlk->state);
 	if (!test_bit(0, &nlk->state))
 		wake_up_interruptible(&nlk->wait);