[S] Change in coreboot[main]: mb/google/nissa: Create sundance variant

[Leo Chou (Code Review)]

Attention is currently required from: Derek Huang, Dinesh Gehlot, Eric Lai, Kapil Porwal, Nick Vaccaro, Shou-Chieh Hsu, Subrata Banik.

Leo Chou has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/81347?usp=email )

Change subject: mb/google/nissa: Create sundance variant
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Patch Set 4:

(2 comments)

Patchset:

PS2:
> Please copied the file in src/third_party/coreboot/util/mainboard/google/nissa/template/

Done

File src/mainboard/google/brya/variants/sundance/memory/Makefile.mk:

https://review.coreboot.org/c/coreboot/+/81347/comment/5997f837_b599149a :
PS2, Line 4: SPD_SOURCES =
> place holder?

Done