[coreboot-gerrit] Change in coreboot[master]: FSP2.0 platforms: Use bootloader reserved memory for BERT

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Furquan Shaikh, Arthur Heymans, Andrey Petrov, Patrick Rudolph.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/55142 )

Change subject: FSP2.0 platforms: Use bootloader reserved memory for BERT
......................................................................

Patch Set 4:

(1 comment)

File src/soc/intel/common/block/systemagent/systemagent.c:

https://review.coreboot.org/c/coreboot/+/55142/comment/5880b338_82d302c6 
PS4, Line 196: Make sure to account for the fact that the FSP saves some of the
             : 	 * reserved RAM for ACPI BERT
> One thing that I fear about is this getting out of sync with rest of the changes for BERT space allo […]

How about a Kconfig, e.g.
```
config FSP_RESERVE_BERT_REGION
   bool
   depends on ACPI_BERT
```

where the memory_init.c code guards adding the space:
```
if (CONFIG(FSP_RESERVE_BERT_REGION))
     march_upd->BootloaderTolumSize += CONFIG_ACPI_BERT_SIZE;
```

and then here
```
if (CONFIG(FSP_RESERVE_BERT_REGION))
      top_of_ram += CONFIG_ACPI_BERT_SIZE;
```