[S] Change in coreboot[main]: vendorcode/google/chromeos: Use unsigned int for "factory_config"

[Tim Van Patten (Code Review)]

Attention is currently required from: Eric Lai, Julius Werner, Kapil Porwal, Shelley Chen, Subrata Banik.

Tim Van Patten has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79769?usp=email )

Change subject: vendorcode/google/chromeos: Use unsigned int for "factory_config"
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Patch Set 1:

(1 comment)

File src/vendorcode/google/chromeos/tpm_factory_config.c:

https://review.coreboot.org/c/coreboot/+/79769/comment/a7abe624_20e4b939 :
PS1, Line 27: 	rc = tlcl_cr50_get_factory_config(&factory_config);
This function should assert `factory_config != CHROMEOS_ERROR` after this call also, to catch any changes in the future that end up using all the bits. Otherwise we're signalling an error to the caller even though it's a valid value (assuming `rc == TPM_SUCCESS`, of course).

This means we're kicking the can in terms of how to signal errors to the caller and/or removing using the MSB as a valid config bit, which I'm fine with since the odds are low that it'll occur. We should have something to alert us when this happens some (long) time in the future though.