wifi: rtw88: simplify __rtw_tx_work()

Since 'ieee80211_txq_get_depth()' allows NULL for 2nd and
3rd arguments, simplify '__rtw_tx_work()' by dropping unused
'byte_cnt'. Compile tested only.
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231102115606.69838-1-dmantipov@yandex.ru

drivers/net/wireless/realtek/rtw88/tx.c

@@ -656,9 +656,8 @@ void __rtw_tx_work(struct rtw_dev *rtwdev)
 	list_for_each_entry_safe(rtwtxq, tmp, &rtwdev->txqs, list) {
 		struct ieee80211_txq *txq = rtwtxq_to_txq(rtwtxq);
 		unsigned long frame_cnt;
-		unsigned long byte_cnt;
 
-		ieee80211_txq_get_depth(txq, &frame_cnt, &byte_cnt);
+		ieee80211_txq_get_depth(txq, &frame_cnt, NULL);
 		rtw_txq_push(rtwdev, rtwtxq, frame_cnt);
 
 		list_del_init(&rtwtxq->list);