mt76: mt7615: fix antenna mask initialization in DBDC mode

Update wiphy available antenna mask, and fix chainmask setting on 3x3 hardware
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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

@@ -350,6 +350,8 @@ mt7615_cap_dbdc_enable(struct mt7615_dev *dev)
 	else
 		dev->mphy.antenna_mask = dev->chainmask >> 1;
 	dev->phy.chainmask = dev->mphy.antenna_mask;
+	dev->mphy.hw->wiphy->available_antennas_rx = dev->phy.chainmask;
+	dev->mphy.hw->wiphy->available_antennas_tx = dev->phy.chainmask;
 	mt76_set_stream_caps(&dev->mt76, true);
 }
 
@@ -361,6 +363,8 @@ mt7615_cap_dbdc_disable(struct mt7615_dev *dev)
 			IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ;
 	dev->mphy.antenna_mask = dev->chainmask;
 	dev->phy.chainmask = dev->chainmask;
+	dev->mphy.hw->wiphy->available_antennas_rx = dev->chainmask;
+	dev->mphy.hw->wiphy->available_antennas_tx = dev->chainmask;
 	mt76_set_stream_caps(&dev->mt76, true);
 }
 

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

@@ -686,7 +686,13 @@ mt7615_set_antenna(struct ieee80211_hw *hw, u32 tx_ant, u32 rx_ant)
 	mutex_lock(&dev->mt76.mutex);
 
 	phy->mt76->antenna_mask = tx_ant;
-	phy->chainmask = ext_phy ? tx_ant << 2 : tx_ant;
+	if (ext_phy) {
+		if (dev->chainmask == 0xf)
+			tx_ant <<= 2;
+		else
+			tx_ant <<= 1;
+	}
+	phy->chainmask = tx_ant;
 
 	mt76_set_stream_caps(&dev->mt76, true);