Replace all calls to g/s_crop by calls to the get/set_selection pad ops.

Remove the old g/s_crop video ops since they are now no longer used.

The cropcap video op is now only used to pass pixelaspect information,
and is only needed if the pixelaspect is not 1:1.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>