wifi: ath9k: cleanup struct ath_tx_control and ath_tx_prepare()

After switching to mac80211 software queues, pointer to 'struct ath_node'
in 'struct ath_tx_control' is still assigned but not actually used. So drop
it and cleanup related things in 'ath_tx_prepare()'. Compile tested only.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20250115171750.259917-1-dmantipov@yandex.ru
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -274,7 +274,6 @@ struct ath_node {
 
 struct ath_tx_control {
 	struct ath_txq *txq;
-	struct ath_node *an;
 	struct ieee80211_sta *sta;
 	u8 paprd;
 };

drivers/net/wireless/ath/ath9k/xmit.c

@@ -2291,19 +2291,10 @@ static int ath_tx_prepare(struct ieee80211_hw *hw, struct sk_buff *skb,
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 	struct ieee80211_sta *sta = txctl->sta;
 	struct ieee80211_vif *vif = info->control.vif;
-	struct ath_vif *avp;
 	struct ath_softc *sc = hw->priv;
 	int frmlen = skb->len + FCS_LEN;
 	int padpos, padsize;
 
-	/* NOTE:  sta can be NULL according to net/mac80211.h */
-	if (sta)
-		txctl->an = (struct ath_node *)sta->drv_priv;
-	else if (vif && ieee80211_is_data(hdr->frame_control)) {
-		avp = (void *)vif->drv_priv;
-		txctl->an = &avp->mcast_node;
-	}
-
 	if (info->control.hw_key)
 		frmlen += info->control.hw_key->icv_len;