arch/x86: Drop CBMEM_TOP_BACKUP

Code has evolved such that there seems to be little
use for global definition of cbmem_top_chipset().
Even for AMD we had three different implementations.

Change-Id: I44805aa49eab526b940e57bd51cd1d9ae0377b4b
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43326
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/amd/stoneyridge/memmap.c b/src/soc/amd/stoneyridge/memmap.c
index 9807905..67a4319 100644
--- a/src/soc/amd/stoneyridge/memmap.c
+++ b/src/soc/amd/stoneyridge/memmap.c
@@ -13,7 +13,7 @@
 #include <arch/bert_storage.h>
 #include <soc/northbridge.h>
 #include <soc/iomap.h>
-#include <amdblocks/acpimmio.h>
+#include <amdblocks/biosram.h>
 
 #if CONFIG(ACPI_BERT)
  #if CONFIG_SMM_TSEG_SIZE == 0x0