v4l2: fix param enumeration for devices without controls
It is valid for V4L2 devices to not implement any controls. QUERYCTRL returns ENOTTY in these cases. Enumerating the controls must not fail in these cases but return no controls.
It is valid for V4L2 devices to not implement any controls. QUERYCTRL returns ENOTTY in these cases. Enumerating the controls must not fail in these cases but return no controls.