[XS] Change in coreboot[main]: fmap: Die immediately on verification failure

[Yu-Ping Wu (Code Review)]

Attention is currently required from: Jakub Czapiga, Julius Werner.

Yu-Ping Wu has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78903?usp=email )

Change subject: fmap: Die immediately on verification failure
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Patch Set 1: Code-Review+1

(2 comments)

File src/lib/fmap.c:

https://review.coreboot.org/c/coreboot/+/78903/comment/ffbb35be_b775c039 :
PS1, Line 42: 	   filled with a tampered FMAP but the later fallback path is fed a valid one. */
Also explain why we want to die even if `!CONFIG(TOCTOU_SAFETY)`?

BTW there's a TODO comment which I think now can be fixed.

```
config TOCTOU_SAFETY
    depends on !VBOOT # TODO: can only allow this once vboot fully integrated
```

https://review.coreboot.org/c/coreboot/+/78903/comment/d36ac012_ae2dcb85 :
PS1, Line 127: sizeof(struct fmap)
Not related to this patch, but this is supposed to be `FMAP_SIZE`, right? (at least for `CONFIG(CBFS_VERIFICATION) && ENV_INITIAL_STAGE`)