[XS] Change in coreboot[main]: treewide: Set up linker files with OPENSBI macro

[Maximilian Brune (Code Review)]

Attention is currently required from: Paul Menzel, Philipp Hug, ron minnich.

Maximilian Brune has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/77975?usp=email )

Change subject: treewide: Set up linker files with OPENSBI macro
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Patch Set 3:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/77975/comment/220d5887_05115983 :
PS1, Line 7: Setup
> Set up

Done

https://review.coreboot.org/c/coreboot/+/77975/comment/914577db_70a60a68 :
PS1, Line 8:
> Is the generated code the same?

There are two distinct differences:
1. It adds an ASSERT. That assert is a build time check though and I build tested both boards.
2. It adds the RISCV_OPENSBI check which will only add the region if opensbi is actually inserted in the build (currently opensbi region is always added for some reason).