Change in coreboot[master]: [WIP] ACPI: Move PICM and _PIC declarations

[Lance Zhao (Code Review)]

Attention is currently required from: Raul Rangel, Mariusz Szafrański, Jonathan Zhang, Kyösti Mälkki, Patrick Rudolph, Piotr Król, Jason Glenesk, Anjaneya "Reddy" Chagam, Michał Żygowski, Marshall Dawson, Johnny Lin, Suresh Bellampalli, Vanessa Eusebio, Morgan Jang, Michal Motyl, Alexander Couzens, Felix Held.
Lance Zhao has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/49905 )

Change subject: [WIP] ACPI: Move PICM and _PIC declarations
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Patch Set 3:

(1 comment)

Patchset:

PS3: 
Yes the _PIC and PICM is almost identical. However I don't think acpigen_extern.asl will expect a method within that. Also according to ACPI spec, _PIC is optional, then we can't have coreboot always have _PIC for every combination of platform.

The following from ACPI 6.3 spec page 341
 Notice that calling this method is optional for OSPM.