[M] Change in coreboot[master]: mainboard: Add SPDX license headers to Makefiles

[Nico Huber (Code Review)]

Attention is currently required from: Felix Singer, Jason Nien, Jeremy Soller, Michael Niewöhner, Martin Roth, Tim Crawford, Tarun Tuli, Martin L Roth, Damien Zammit, Subrata Banik, Maxim Polyakov, Kapil Porwal, Alexander Couzens, Werner Zeh, Evgeny Zinoviev.

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/68982 )

Change subject: mainboard: Add SPDX license headers to Makefiles
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Patch Set 2:

(1 comment)

Patchset:

PS2:
> I don't understand these questions.  I don't know if anyone other than AMD is running license scans, but I am writing the patches, and Matt signed off on them.  We're both AMD employees.

Oh, I'm very sorry. I have heard of demands from other companies before (or
at least I think I did) and didn't know AMD is directly involved.

You can generally prevent confusing questions by stating your reasons in the
commit message. e.g. why change? why GPL? is there a rule (missing)?

Now that I read "license scans" what would interest me most: Is this only
done because a tool told us to or is there a human advice behind it?
> As far as the license used, the license of coreboot as a whole is GPL V2.  If someone contributes a file and doesn't specify a different license, the license defaults to GPL V2 as a part of the coreboot project.  These patches just clarify that the Makefile are licensed under GPL V2.

Is this documented somewhere? As the top-level Makefile is BSD licensed, I
would have guessed otherwise.