[media] v4l2 subdevs: replace get/set_crop by get/set_selection

The crop and selection pad ops are duplicates. Replace all uses of get/set_crop
by get/set_selection. This will make it possible to drop get/set_crop
altogether.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Prabhakar Lad <prabhakar.csengg@gmail.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>