mac80211: move TX station pointer and restructure TX

Remove the control.sta pointer from ieee80211_tx_info to free up
sufficient space in the TX skb control buffer for the upcoming
Transmit Power Control (TPC).
Instead, the pointer is now on the stack in a new control struct
that is passed as a function parameter to the drivers' tx method.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: Alina Friedrichsen <x-alina@gmx.net>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
[reworded commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 2c9da6b..ef91f6c 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1773,11 +1773,12 @@
 	TX_STAT_INC(txq->axq_qnum, queued);
 }
 
-static void setup_frame_info(struct ieee80211_hw *hw, struct sk_buff *skb,
+static void setup_frame_info(struct ieee80211_hw *hw,
+			     struct ieee80211_sta *sta,
+			     struct sk_buff *skb,
 			     int framelen)
 {
 	struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
-	struct ieee80211_sta *sta = tx_info->control.sta;
 	struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	const struct ieee80211_rate *rate;
@@ -1935,7 +1936,7 @@
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-	struct ieee80211_sta *sta = info->control.sta;
+	struct ieee80211_sta *sta = txctl->sta;
 	struct ieee80211_vif *vif = info->control.vif;
 	struct ath_softc *sc = hw->priv;
 	struct ath_txq *txq = txctl->txq;
@@ -1979,7 +1980,7 @@
 	    !ieee80211_is_data(hdr->frame_control))
 		info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
 
-	setup_frame_info(hw, skb, frmlen);
+	setup_frame_info(hw, sta, skb, frmlen);
 
 	/*
 	 * At this point, the vif, hw_key and sta pointers in the tx control