[media] media: ov5642: Add support for arbitrary resolution

This patch adds the ability to get arbitrary resolutions with a width
up to 2592 and a height up to 720 pixels instead of the standard 1280x720
only.

Signed-off-by: Bastian Hecht <hechtb@gmail.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>