net: add skb_get_tx_queue() helper

Replace occurences of skb_get_queue_mapping() and follow-up
netdev_get_tx_queue() with an actual helper function.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index fc04fe9..05b3f5d 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -63,7 +63,7 @@
 
 	if (unlikely(skb)) {
 		/* check the reason of requeuing without tx lock first */
-		txq = netdev_get_tx_queue(txq->dev, skb_get_queue_mapping(skb));
+		txq = skb_get_tx_queue(txq->dev, skb);
 		if (!netif_xmit_frozen_or_stopped(txq)) {
 			q->gso_skb = NULL;
 			q->q.qlen--;
@@ -183,10 +183,12 @@
 	skb = dequeue_skb(q);
 	if (unlikely(!skb))
 		return 0;
+
 	WARN_ON_ONCE(skb_dst_is_noref(skb));
+
 	root_lock = qdisc_lock(q);
 	dev = qdisc_dev(q);
-	txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
+	txq = skb_get_tx_queue(dev, skb);
 
 	return sch_direct_xmit(skb, q, dev, txq, root_lock);
 }