rt2x00: Add kill_tx_queue callback function

provide rt2x00lib the possibility to kill a particular TX queue.
This can be useful when disabling the radio, but more importantly
will allow beaconing to be disabled when mac80211 requests this
(during scanning for example)

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index d0a8256..94fb571 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -508,6 +508,8 @@
 	int (*get_tx_data_len) (struct queue_entry *entry);
 	void (*kick_tx_queue) (struct rt2x00_dev *rt2x00dev,
 			       const enum data_queue_qid queue);
+	void (*kill_tx_queue) (struct rt2x00_dev *rt2x00dev,
+			       const enum data_queue_qid queue);
 
 	/*
 	 * RX control handlers