Bluetooth: btusb: fix memory leak on fw

Currently the error return path when the call to btusb_mtk_hci_wmt_sync
fails does not free fw.  Fix this by returning via the error_release_fw
label that performs the free'ing.

Addresses-Coverity: ("Resource leak")
Fixes: a1c49c43 ("Bluetooth: btusb: Add protocol support for MediaTek MT7668U USB devices")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btusb.c

@@ -2867,7 +2867,7 @@ static int btusb_mtk_setup_firmware(struct hci_dev *hdev, const char *fwname)
 	err = btusb_mtk_hci_wmt_sync(hdev, &wmt_params);
 	if (err < 0) {
 		bt_dev_err(hdev, "Failed to send wmt rst (%d)", err);
-		return err;
+		goto err_release_fw;
 	}
 
 	/* Wait a few moments for firmware activation done */