wifi: mt76: mt7615: do not advertise 5 GHz on first phy of MT7615D (DBDC)

On DBDC devices the first (internal) phy is only capable of using
2.4 GHz band, and the 5 GHz band is exposed via a separate phy object,
so avoid the false advertising.
Reported-by: Rani Hod <rani.hod@gmail.com>
Closes: https://github.com/openwrt/openwrt/pull/12361
Fixes: 7660a1bd ("mt76: mt7615: register ext_phy if DBDC is detected")
Cc: stable@vger.kernel.org
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230605073408.8699-1-fercerpav@gmail.com

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

@@ -128,12 +128,12 @@ mt7615_eeprom_parse_hw_band_cap(struct mt7615_dev *dev)
 	case MT_EE_5GHZ:
 		dev->mphy.cap.has_5ghz = true;
 		break;
-	case MT_EE_2GHZ:
-		dev->mphy.cap.has_2ghz = true;
-		break;
 	case MT_EE_DBDC:
 		dev->dbdc_support = true;
 		fallthrough;
+	case MT_EE_2GHZ:
+		dev->mphy.cap.has_2ghz = true;
+		break;
 	default:
 		dev->mphy.cap.has_2ghz = true;
 		dev->mphy.cap.has_5ghz = true;