MT#55283 poll_wait before checking status

This follows the usual polling design pattern

Change-Id: If7797640d96e567deb6dcbb36a5696c6de40b431

kernel-module/xt_RTPENGINE.c

@@ -3438,6 +3438,8 @@ static unsigned int proc_stream_poll(struct file *f, struct poll_table_struct *p
 	if (!stream)
 		return POLLERR;
 
+	poll_wait(f, &stream->read_wq, p);
+
 	DBG("locking stream's packet list lock\n");
 	spin_lock_irqsave(&stream->packet_list_lock, flags);
 
@@ -3448,8 +3450,6 @@ static unsigned int proc_stream_poll(struct file *f, struct poll_table_struct *p
 
 	spin_unlock_irqrestore(&stream->packet_list_lock, flags);
 
-	poll_wait(f, &stream->read_wq, p);
-
 	stream_put(stream);
 
 	return ret;