Bluetooth: btusb: Return error code when getting patch status failed

If there are failure cases in getting patch status, it should return the
error code (-EIO).

Fixes: fc342c4dc4 ("Bluetooth: btusb: Add protocol support for MediaTek MT7921U USB devices")
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Mark Chen <mark-yw.chen@mediatek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btmtk.c

@@ -121,6 +121,7 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 				} else {
 					bt_dev_err(hdev, "Failed wmt patch dwnld status (%d)",
 						   status);
+					err = -EIO;
 					goto err_release_fw;
 				}
 			}