[XS] Change in coreboot[main]: mb/google/oak: Don't build the ChromeEC codebase by default

[Hung-Te Lin (Code Review)]

Attention is currently required from: Martin L Roth, Yidi Lin, Yu-Ping Wu.

Hung-Te Lin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/81023?usp=email )

Change subject: mb/google/oak: Don't build the ChromeEC codebase by default
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Patch Set 2:

(1 comment)

Patchset:

PS2: 
Do we know why Oak needs to build ChromeEC? Can we just replace that with something equivalent that other boards are using?