media: radio-si476x: Unregister v4l2_device on probe failure

media: radio-si476x: Unregister v4l2_device on probe failure

si476x_radio_probe() registers radio->v4l2dev before allocating the V4L2
controls and before registering the video device. If any of those later
steps fails, probe returns through the exit label after freeing only the
control handler.

A failed probe does not call si476x_radio_remove(), so the
v4l2_device_unregister() there is not reached. This leaves the parent
device reference taken by v4l2_device_register() behind on the error path.

Unregister the V4L2 device in the probe error path after freeing the
controls.

Fixes: b879a9c2a755 ("[media] v4l2: Add a V4L2 driver for SI476X MFD")
Cc: stable@vger.kernel.org
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>