[M] Change in coreboot[main]: mb: source site-local mainboard Kconfig.name and Kconfig files

[David Hendricks (Code Review)]

Attention is currently required from: Alexander Couzens, Evgeny Zinoviev, Felix Held, Felix Singer, Jeremy Soller, Jonathon Hall, Martin L Roth, Matt DeVillier, Michael Niewöhner, Michał Żygowski, Philipp Hug, Piotr Król, Ron Minnich, Sean Rhodes, Tim Crawford.

David Hendricks has posted comments on this change by Martin L Roth. ( https://review.coreboot.org/c/coreboot/+/83119?usp=email )

Change subject: mb: source site-local mainboard Kconfig.name and Kconfig files
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Patch Set 2: Code-Review+1

(1 comment)

Patchset:

PS2: 
I like this idea, but does it need to be applied broadly? Maybe it's best to keep the added `source` lines where it's most likely needed (silicon vendor mainboard targets, among perhaps a few others) and document the rationale in https://doc.coreboot.org/tutorial/managing_local_additions.html#integration-....

OTOH, doing it broadly helps with overall uniformity of the Kconfig files and makes site-local usage a bit more obvious.