Change in coreboot[master]: soc/intel/common/block/notify: Implement coreboot notify native driver

[Subrata Banik (Code Review)]

Attention is currently required from: Arthur Heymans, Felix Singer, Tim Wawrzynczak, Sridhar Siricilla, Angel Pons, Lean Sheng Tan, Werner Zeh, Patrick Rudolph, EricR Lai.
Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/60405 )

Change subject: soc/intel/common/block/notify: Implement coreboot notify native driver
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Patch Set 21:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/60405/comment/2ebe1a03_afd495e2 
PS19, Line 7: soc/intel/common/block/notify: Implement coreboot notify native driver
> Thanks for views.. my worry part is, if you switch off the FSP Notify code, and enables coreboot native code in this regard, then we might end-up loose changes if SOC team adds in the FSP notify API though the changes are optional. My concern is with respect to maintenance.

Valid concern and we can have few strategies to ensure robustness

1. Refer to the SoC platform FAS security chapter and implement those recommended programming (ideally those are meant for OEM/ODM to implement, all IBVs do refer to the same document).

2. Intel can own this piece like what is being done YoY for Cache-as-RAM native code in `soc/intel/common/block/cpu/car`, eNEM as replacement for FSP-T for each SoC program. (on ADL it took several months to validate eNEM and enable finally) In the past we didn't pick FSP-T just to avoid extra enabling time for CAR/eNEM, right?

Please share your thoughts on this.