rt2x00: Implement rt2x00usb_kick_tx_queue()

rt2x00usb_kick_tx_queue() will loop over all entries
within the INDEX_DONE->INDEX range and kick each entry
which is pending to be kicked. This makes the kick_tx_queue
approach work the same as with the PCI drivers which
will allow for more code generalisation into rt2x00lib.

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/rt2x00queue.h b/drivers/net/wireless/rt2x00/rt2x00queue.h
index 4d00ced..303d556 100644
--- a/drivers/net/wireless/rt2x00/rt2x00queue.h
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.h
@@ -260,11 +260,14 @@
  * @ENTRY_OWNER_DEVICE_CRYPTO: This entry is owned by the device for data
  *	encryption or decryption. The entry should only be touched after
  *	the device has signaled it is done with it.
+ * @ENTRY_DATA_PENDING: This entry contains a valid frame and is waiting
+ *	for the signal to start sending.
  */
 enum queue_entry_flags {
 	ENTRY_BCN_ASSIGNED,
 	ENTRY_OWNER_DEVICE_DATA,
 	ENTRY_OWNER_DEVICE_CRYPTO,
+	ENTRY_DATA_PENDING,
 };
 
 /**