wifi: mt76: do not add non-sta wcid entries to the poll list

jira KERNEL-238
Rebuild_History Non-Buildable kernel-6.12.0-124.16.1.el10_1
commit-author Felix Fietkau <nbd@nbd.name>
commit a3c99ef

Polling and airtime reporting is valid for station entries only

Link: https://patch.msgid.link/20250827085352.51636-2-nbd@nbd.name
	Signed-off-by: Felix Fietkau <nbd@nbd.name>
(cherry picked from commit a3c99ef)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

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

@@ -1688,7 +1688,7 @@ EXPORT_SYMBOL_GPL(mt76_wcid_cleanup);
 
 void mt76_wcid_add_poll(struct mt76_dev *dev, struct mt76_wcid *wcid)
 {
-	if (test_bit(MT76_MCU_RESET, &dev->phy.state))
+	if (test_bit(MT76_MCU_RESET, &dev->phy.state) || !wcid->sta)
 		return;
 
 	spin_lock_bh(&dev->sta_poll_lock);