[media] ov2640: use the v4l2 size definitions

Reuse the v4l2 size definitions from v4l2-image-sizes.h.
So we can remove the rudundent definitions from ov2640.c.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>