Change in coreboot[master]: amdfwtool: Use relative address for EFS gen2

[Karthik Ramasubramanian (Code Review)]

Attention is currently required from: Bao Zheng, Martin Roth, Marshall Dawson, Kangheui Won, Paul Menzel, Zheng Bao, Eric Peers, Karthikeyan Ramasubramanian, Felix Held.
Karthik Ramasubramanian has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/56438 )

Change subject: amdfwtool: Use relative address for EFS gen2
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Patch Set 15:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/56438/comment/88cd0a3d_431aeb3a 
PS2, Line 9: The second generation EFS (offset 0x24[0]=0) uses
           : "binary relative" offsets and not "x86 physical
           : MMIO address" like gen1.
           : 
           : Chips like Cezanne can run in both cases, so no problem
           : comes up so far.
           : 
           : TODO: Need to fix the problem in psp_verstage.
> Done

We still need to wait until the PSP verstage is signed and signed verstage is landed in the downstream tree. ETA - 11/08/2021.