[media] V4L: pxa_camera: remove redundant calculations

soc_camera core now performs the standard .bytesperline and .sizeimage
calculations internally, no need to duplicate in drivers.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>