Bluetooth: hci_serdev: Only unregister device if it was registered

We should not call hci_unregister_dev if the device was not
successfully registered.

Fixes: c34dc3bfa7 ("Bluetooth: hci_serdev: Introduce hci_uart_unregister_device()")
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_serdev.c

@@ -355,7 +355,8 @@ void hci_uart_unregister_device(struct hci_uart *hu)
 	struct hci_dev *hdev = hu->hdev;
 
 	clear_bit(HCI_UART_PROTO_READY, &hu->flags);
-	hci_unregister_dev(hdev);
+	if (test_bit(HCI_UART_REGISTERED, &hu->flags))
+		hci_unregister_dev(hdev);
 	hci_free_dev(hdev);
 
 	cancel_work_sync(&hu->write_work);