mt76: mt7615: fix event report in mt7615_mcu_bss_event

Currently mt7663 devices do not support DBDC so fw events have no info
about it. Fix mt7615_mcu_bss_event that wrongly use bss_idx as DBDC
band_idx while it is vif index.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/mcu.c

@@ -356,11 +356,12 @@ mt7615_mcu_bss_event(struct mt7615_dev *dev, struct sk_buff *skb)
 {
 	struct mt7615_mcu_bss_event *event;
 	struct mt76_phy *mphy;
+	u8 band_idx = 0; /* DBDC support */
 
 	event = (struct mt7615_mcu_bss_event *)(skb->data +
 						sizeof(struct mt7615_mcu_rxd));
 
-	if (event->bss_idx && dev->mt76.phy2)
+	if (band_idx && dev->mt76.phy2)
 		mphy = dev->mt76.phy2;
 	else
 		mphy = &dev->mt76.phy;