[media] media: platform: pxa_camera: remove set_selection

This is to be seen as a regression as the set_selection (former
set_crop) function is removed. This is a temporary situation in the v4l2
porting, and will have to be added later.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>