rt2x00: Simplify TXD handling of beacons.

The handling of tx descriptors for beacons can be simplified by updating
write_tx_desc implementations of each driver to write directly to the
queue entry descriptor instead of to a provided memory area.
This is also a preparation for further clean ups where descriptors are
properly reserved in the skb instead of fiddling with the skb data
pointer.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2800usb.c b/drivers/net/wireless/rt2x00/rt2800usb.c
index d48d705..1b87daa 100644
--- a/drivers/net/wireless/rt2x00/rt2800usb.c
+++ b/drivers/net/wireless/rt2x00/rt2800usb.c
@@ -400,7 +400,7 @@
 				    struct txentry_desc *txdesc)
 {
 	struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
-	__le32 *txi = skbdesc->desc;
+	__le32 *txi = (__le32 *)(skb->data - TXWI_DESC_SIZE - TXINFO_DESC_SIZE);
 	u32 word;
 
 	/*
@@ -422,6 +422,12 @@
 	rt2x00_set_field32(&word, TXINFO_W0_USB_DMA_TX_BURST,
 			   test_bit(ENTRY_TXD_BURST, &txdesc->flags));
 	rt2x00_desc_write(txi, 0, word);
+
+	/*
+	 * Register descriptor details in skb frame descriptor.
+	 */
+	skbdesc->desc = txi;
+	skbdesc->desc_len = TXINFO_DESC_SIZE + TXWI_DESC_SIZE;
 }
 
 /*