net_sched: Add qdisc __NET_XMIT_BYPASS flag

Patrick McHardy <kaber@trash.net> noticed that it would be nice to
handle NET_XMIT_BYPASS by NET_XMIT_SUCCESS with an internal qdisc flag
__NET_XMIT_BYPASS and to remove the mapping from dev_queue_xmit().

David Miller <davem@davemloft.net> spotted a serious bug in the first
version of this patch.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 6cd6f2b..fb0294d 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -176,7 +176,7 @@
 	if (count == 0) {
 		sch->qstats.drops++;
 		kfree_skb(skb);
-		return NET_XMIT_BYPASS;
+		return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	}
 
 	skb_orphan(skb);