media: rkisp1: resizer: Constify argument and local variables

Pointers to v4l2_mbus_framefmt and v4l2_rect instances don't need to be
modified when configuring the resizer. Make them const.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>