v4l2-ctl: Operate on output device if specified

The video output get, set and list options operate on the device set by
--device, even if the --out-device option is specified to select a
different output device. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>