[NET_SCHED]: sch_netem: fix off-by-one in send time comparison

netem checks PSCHED_TLESS(cb->time_to_send, now) to find out whether it is
allowed to send a packet, which is equivalent to cb->time_to_send < now.
Use !PSCHED_TLESS(now, cb->time_to_send) instead to properly handle
cb->time_to_send == now.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_netem.c

@@ -286,7 +286,7 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 		/* if more time remaining? */
 		PSCHED_GET_TIME(now);
 
-		if (PSCHED_TLESS(cb->time_to_send, now)) {
+		if (!PSCHED_TLESS(now, cb->time_to_send)) {
 			pr_debug("netem_dequeue: return skb=%p\n", skb);
 			sch->q.qlen--;
 			return skb;