Bluetooth: btusb: Fix the patch for MT7920 the affected to MT7921

Because both MT7920 and MT7921 use the same chip ID.
We use the 8th bit of fw_flavor to distingush MT7920.
The original patch made a mistake to check whole fw_flavor,
that makes the condition both true (dev_id == 0x7961 && fw_flavor),
and makes MT7921 flow wrong.

In this patch, we correct the flow to get the 8th bit value for MT7920.
And the patch is verified pass with both MT7920 and MT7921.
Signed-off-by: Peter Tsao <peter.tsao@mediatek.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

drivers/bluetooth/btusb.c

@@ -3123,6 +3123,7 @@ static int btusb_mtk_setup(struct hci_dev *hdev)
 			bt_dev_err(hdev, "Failed to get fw flavor (%d)", err);
 			return err;
 		}
+		fw_flavor = (fw_flavor & 0x00000080) >> 7;
 	}
 
 	mediatek = hci_get_priv(hdev);