net: pktgen: Use wait_event_freezable_timeout() for freezable kthread

A freezable kernel thread can enter frozen state during freezing by
either calling try_to_freeze() or using wait_event_freezable() and its
variants. So for the following snippet of code in a kernel thread loop:
  wait_event_interruptible_timeout();
  try_to_freeze();

We can change it to a simple wait_event_freezable_timeout() and then
eliminate a function call.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/pktgen.c

@@ -3669,10 +3669,8 @@ static int pktgen_thread_worker(void *arg)
 		if (unlikely(!pkt_dev && t->control == 0)) {
 			if (t->net->pktgen_exiting)
 				break;
-			wait_event_interruptible_timeout(t->queue,
-							 t->control != 0,
-							 HZ/10);
-			try_to_freeze();
+			wait_event_freezable_timeout(t->queue,
+						     t->control != 0, HZ / 10);
 			continue;
 		}