Move the definition of the dewarper stop() action into the scope were
the corresponding start() happens.
Fixes: 12b553d691 ("libcamera: rkisp1: Plumb the dw100 dewarper as V4L2M2M converter")
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>