mac80211: free up 2 bytes in skb->cb

Free up 2 bytes in skb->cb to be used for multi-rate retry later.
Move iv_len and icv_len initialization into key alloc.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/xmit.c b/drivers/net/wireless/ath9k/xmit.c
index bdcb9e1..3a47579 100644
--- a/drivers/net/wireless/ath9k/xmit.c
+++ b/drivers/net/wireless/ath9k/xmit.c
@@ -237,7 +237,7 @@
 
 	if (tx_info->control.hw_key) {
 		txctl->keyix = tx_info->control.hw_key->hw_key_idx;
-		txctl->frmlen += tx_info->control.icv_len;
+		txctl->frmlen += tx_info->control.hw_key->icv_len;
 
 		if (tx_info->control.hw_key->alg == ALG_WEP)
 			txctl->keytype = ATH9K_KEY_TYPE_WEP;