amd/stoneyridge: Set BERT region size when no TSEG used

Expand the BERT reserved region size setting to account for the
possibility of no TSEG configuration.  This change is only for
completeness, as stoneyridge must always use TSEG.

Change-Id: I90753fa408cfac4de38aff08979c45349bb62a66
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/28554
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marc Jones <marc@marcjonesconsulting.com>

src/soc/amd/stoneyridge/ramtop.c

@@ -38,8 +38,12 @@ uintptr_t restore_top_of_low_cacheable(void)
 }
 
 #if IS_ENABLED(CONFIG_ACPI_BERT)
+ #if CONFIG_SMM_TSEG_SIZE == 0x0
+  #define BERT_REGION_MAX_SIZE 0x100000
+ #else
   /* SMM_TSEG_SIZE must stay on a boundary appropriate for its granularity */
   #define BERT_REGION_MAX_SIZE CONFIG_SMM_TSEG_SIZE
+ #endif
 #else
  #define BERT_REGION_MAX_SIZE 0
 #endif