net: avoid to call skb_queue_len again

the queue length of sd->input_pkt_queue has been put into qlen,
and impossible to change, since hold the lock

Signed-off-by: Li RongQing <[e-mail]>
Acked-by: Eric Dumazet <[e-mail]>
Cc: Sergei Shtylyov <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/core/dev.c

···
 	rps_lock(sd);
 	qlen = skb_queue_len(&sd->input_pkt_queue);
 	if (qlen <= netdev_max_backlog && !skb_flow_limit(skb, qlen)) {
-		if (skb_queue_len(&sd->input_pkt_queue)) {
+		if (qlen) {
 enqueue:
 			__skb_queue_tail(&sd->input_pkt_queue, skb);
 			input_queue_tail_incr_save(sd, qtail);