The v4l function has a better algorithm for aligning image size.

Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>