rt2x00: Move generic TX frame writing code into rt2x00queue

The write_tx_data functions in rt2x00pci and rt2x00usb have
a lot in common. This moves that duplicate code into
rt2x00queue_write_tx_frame().

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/rt2x00lib.h b/drivers/net/wireless/rt2x00/rt2x00lib.h
index c4ce534..558f45b 100644
--- a/drivers/net/wireless/rt2x00/rt2x00lib.h
+++ b/drivers/net/wireless/rt2x00/rt2x00lib.h
@@ -101,6 +101,7 @@
 /*
  * Queue handlers.
  */
+int rt2x00queue_write_tx_frame(struct data_queue *queue, struct sk_buff *skb);
 void rt2x00queue_init_rx(struct rt2x00_dev *rt2x00dev);
 void rt2x00queue_init_tx(struct rt2x00_dev *rt2x00dev);
 int rt2x00queue_initialize(struct rt2x00_dev *rt2x00dev);