The V4L2VideoDevice class implements setSelection() but not getSelection(). The latter is useful for instance to query crop bounds. Implement the function. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Umang Jain <umang.jain@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>