[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/irda/irttp.c b/net/irda/irttp.c
index d091ccf..6602d90 100644
--- a/net/irda/irttp.c
+++ b/net/irda/irttp.c
@@ -1513,7 +1513,7 @@
 	/*
 	 *  Check if there is still data segments in the transmit queue
 	 */
-	if (skb_queue_len(&self->tx_queue) > 0) {
+	if (!skb_queue_empty(&self->tx_queue)) {
 		if (priority == P_HIGH) {
 			/*
 			 *  No need to send the queued data, if we are