rt2x00: Register frame length in TX entry descriptor instead of L2PAD.

And use it consistently in the chipset drivers.
Preparation for further clean ups.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2800pci.c b/drivers/net/wireless/rt2x00/rt2800pci.c
index 89281d7..f08b6a3 100644
--- a/drivers/net/wireless/rt2x00/rt2800pci.c
+++ b/drivers/net/wireless/rt2x00/rt2800pci.c
@@ -663,7 +663,7 @@
 			   test_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags) ?
 			   txdesc->key_idx : 0xff);
 	rt2x00_set_field32(&word, TXWI_W1_MPDU_TOTAL_BYTE_COUNT,
-			   skb->len - txdesc->l2pad);
+			   txdesc->length);
 	rt2x00_set_field32(&word, TXWI_W1_PACKETID,
 			   skbdesc->entry->queue->qid + 1);
 	rt2x00_desc_write(txwi, 1, word);