Change in coreboot[master]: {cpu/x86, drivers/amd}: Use `get_var_mtrr_count()` to get MTRR count

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Subrata Banik, Angel Pons, Nick Vaccaro, Kane Chen, Werner Zeh.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/63219 )

Change subject: {cpu/x86, drivers/amd}: Use `get_var_mtrr_count()` to get MTRR count
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Patch Set 1:

(1 comment)

File src/cpu/x86/mp_init.c:

https://review.coreboot.org/c/coreboot/+/63219/comment/9027f8ec_afa1876a 
PS1, Line 254: 0xff
> > can be another patch, but should be updated to `MTRR_CAP_VCNT` […]

Oops I wrote this too early in the morning, this is fine 😄