Change in coreboot[master]: payloads/tianocore: Allow custom build parameters for custom builds

[Michał Żygowski (Code Review)]

Attention is currently required from: Martin Roth, Michał Kopeć, Stefan Reinauer, Michael Niewöhner.
Michał Żygowski has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62497 )

Change subject: payloads/tianocore: Allow custom build parameters for custom builds
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Patch Set 3:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/62497/comment/77e41d68_f4aec94d 
PS1, Line 9: allowed
> what do you mean by allowed?

ALmost all payload are built from hardcoded git repos. Not so long ago TianoCore payload could be built from the upstream repo only, then it changed to upstream vs Mr Chromebox repo and now we can specify own URL for the TianoCore repo. This is first such case I see in coreboot, thus the use of "allowed".

Patchset:

PS1:
> This change could be separated from the patch train, so we can get it in faster :)

If it gets +2, we don;t mind rebasing it on master to apply