[coreboot-gerrit] Change in coreboot[master]: mb/google/puff: enable retraining memory support

[Arthur Heymans (Code Review)]

Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/39140 )

Change subject: mb/google/puff: enable retraining memory support
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Patch Set 1:

Comparing SPD's is not mainboard specific at all. I suggest putting those in ddr4 specific and FSP (for UPD pointers) helper functions.