Change in coreboot[master]: sc7280: Improve performance by removing delays in cpucp init

[Julius Werner (Code Review)]

Attention is currently required from: Ravi Kumar Bokka, Martin L Roth, Paul Menzel, Sudheer Amrabadi.
Julius Werner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/63085 )

Change subject: sc7280: Improve performance by removing delays in cpucp init
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Patch Set 25:

(1 comment)

File src/mainboard/google/herobrine/romstage.c:

https://review.coreboot.org/c/coreboot/+/63085/comment/ba66ff70_cf5cdb5c 
PS24, Line 22: prepare();
> Ack

We don't have separate mainboard and chipset hooks for romstage on arm64, so this needs to be done here for now. We could introduce a mechanism for that if it becomes a frequent problem. Until this, our romstage hook needs have pretty much always been mainboard-specific so there hasn't really been a need yet.