rt2x00: Use unlikely for error case in rt2x00queue_write_tx_frame

This is an error condition that is not supposed to happen. Hence, it is
safe to add unlikely to this check.
Signed-off-by: NHelmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00queue.c

@@ -489,7 +489,8 @@ int rt2x00queue_write_tx_frame(struct data_queue *queue, struct sk_buff *skb,
 	if (unlikely(rt2x00queue_full(queue)))
 		return -ENOBUFS;
 
-	if (test_and_set_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags)) {
+	if (unlikely(test_and_set_bit(ENTRY_OWNER_DEVICE_DATA,
+				      &entry->flags))) {
 		ERROR(queue->rt2x00dev,
 		      "Arrived at non-free entry in the non-full queue %d.\n"
 		      "Please file bug report to %s.\n",