net: Add a missing local_irq_enable()

As noticed by Changli Gao, we must call local_irq_enable() after
rps_unlock()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -3121,6 +3121,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
 		if (!skb) {
 			__napi_complete(napi);
 			rps_unlock(queue);
+			local_irq_enable();
 			break;
 		}
 		rps_unlock(queue);