kconfig: automatically include mainboards

This change switches all mainboard vendors and mainboards
to be autoincluded by Kconfig, rather than having to be mentioned

This means, vendor and mainboard directories are becoming more
"drop in", e.g. be placed in the coreboot directory hierarchy
without having to modify any higher level coreboot files.

The long term plan is to enable out of tree mainboards / components
to be built with a given coreboot version (given that the API did
not change)

Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Change-Id: Ib68ce1478a2e12562aeac6297128a21eb174d58a
Reviewed-on: http://review.coreboot.org/9295
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
370 files changed