Give layouts their own type

Introduce `struct flashrom_layout` and refactor layout.c a little, so
we can reuse the layout from there and have other sources of layouts
beside it.

I didn't want to clutter up flash.h any more. So things went into a new
layout.h.

Change-Id: Icea1a58c283131cc9c5fde6f16d783538dc1a4c7
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/17944
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
3 files changed