Change in coreboot[master]: {mb, soc}: Move mrc_cache invalidating logic into `memory` common code

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Subrata Banik, Nick Vaccaro, Patrick Rudolph, Zhuohao Lee.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62738 )

Change subject: {mb, soc}: Move mrc_cache invalidating logic into `memory` common code
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Patch Set 4: Code-Review+2