mt7601u: lock out rx path and tx status reporting

mac80211 requires that rx path does not run concurrently with
tx status reporting.  Add a spinlock which will ensure that.

Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt7601u/mac.c

@@ -182,9 +182,9 @@ void mt76_send_tx_status(struct mt7601u_dev *dev, struct mt76_tx_status *stat)
 
 	mt76_mac_fill_tx_status(dev, &info, stat);
 
-	local_bh_disable();
+	spin_lock_bh(&dev->mac_lock);
 	ieee80211_tx_status_noskb(dev->hw, sta, &info);
-	local_bh_enable();
+	spin_unlock_bh(&dev->mac_lock);
 
 	rcu_read_unlock();
 }