[L] Change in coreboot[master]: soc/amd: Define AMD_FWM_POSITION config item

[Karthik Ramasubramanian (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Matt DeVillier, Arthur Heymans, Fred Reitberger, Felix Held.

Karthik Ramasubramanian has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/68584 )

Change subject: soc/amd: Define AMD_FWM_POSITION config item
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Patch Set 4:

(1 comment)

File src/soc/amd/common/block/psp/Kconfig:

https://review.coreboot.org/c/coreboot/+/68584/comment/72299abb_8c44c681 
PS4, Line 87: default 0xFFFA0000 if AMD_FWM_POSITION_INDEX = 0
            : 	default 0xFFF20000 if AMD_FWM_POSITION_INDEX = 1
            : 	default 0xFFE20000 if AMD_FWM_POSITION_INDEX = 2
            : 	default 0xFFC20000 if AMD_FWM_POSITION_INDEX = 3
            : 	default 0xFF820000 if AMD_FWM_POSITION_INDEX = 4
            : 	default 0xFF020000 if AMD_FWM_POSITION_INDEX = 5
> This needs to be an offset in flash, not in x86 memory mapped space?

Unfortunately amdfwtool expects it to be x86 memory mapped space. There seems to be an assumption that the the last 16MB (0xff000000 - 0xffffffff) in the x86 32 bit memory map is where the SPI flash is present even if it's size is 16 MB or not. So it has to be an offset in that 16 MB. I will look for a best way to change it.