mt76: fix handling ps-poll frames

[ Upstream commit 36d910960fae3f9e74bedf3e0ef39ee26bdaa51f ]

Hardware station lookup for pspoll frames can fail, which makes the driver
ignore ps-poll frames. Fix the resulting powersave issues by looking up
the station for pspoll frames in software
Signed-off-by: NFelix Fietkau <nbd@nbd.name>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/net/wireless/mediatek/mt76/mac80211.c

@@ -548,6 +548,12 @@ mt76_check_ps(struct mt76_dev *dev, struct sk_buff *skb)
 	struct mt76_wcid *wcid = status->wcid;
 	bool ps;
 
+	if (ieee80211_is_pspoll(hdr->frame_control) && !wcid) {
+		sta = ieee80211_find_sta_by_ifaddr(dev->hw, hdr->addr2, NULL);
+		if (sta)
+			wcid = status->wcid = (struct mt76_wcid *) sta->drv_priv;
+	}
+
 	if (!wcid || !wcid->sta)
 		return;