ath9k: Revamp transmit control block

Use the ath_buf instance associated with each tx frame
directly and remove all redundant information in ath_tx_control.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/beacon.c b/drivers/net/wireless/ath9k/beacon.c
index 9e15c30..b36d3fb 100644
--- a/drivers/net/wireless/ath9k/beacon.c
+++ b/drivers/net/wireless/ath9k/beacon.c
@@ -114,7 +114,7 @@
 	ath9k_hw_set11n_txdesc(ah, ds,
 			       skb->len + FCS_LEN,     /* frame length */
 			       ATH9K_PKT_TYPE_BEACON,  /* Atheros packet type */
-			       avp->av_btxctl.txpower, /* txpower XXX */
+			       MAX_RATE_POWER,         /* FIXME */
 			       ATH9K_TXKEYIX_INVALID,  /* no encryption */
 			       ATH9K_KEY_TYPE_CLEAR,   /* no encryption */
 			       flags                   /* no ack,