amdblocks/acpimmio: Unify BIOSRAM usage

All AMD CPU families supported in coreboot have BIOSRAM space. Looking at
the source code, every family could have the same API to save and restore
cbmem top or UMA base and size.

Unify BIOSRAM layout and add implementation for cbmem top and UMA storing.
Also replace the existing implementation of cbmem top and UMA with the
BIOSRAM access.

TEST=boot PC Engines apu1 and apu2

Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Change-Id: I69a03e4f01d7fb2ffc9f8b5af73d7e4e7ec027da
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37402
Reviewed-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/stoneyridge/northbridge.c

@@ -13,6 +13,7 @@
  * GNU General Public License for more details.
  */
 
+#include <amdblocks/biosram.h>
 #include <device/pci_ops.h>
 #include <arch/ioapic.h>
 #include <arch/acpi.h>
@@ -32,7 +33,6 @@
 #include <agesa_headers.h>
 #include <soc/cpu.h>
 #include <soc/northbridge.h>
-#include <soc/southbridge.h>
 #include <soc/pci_devs.h>
 #include <soc/iomap.h>
 #include <stdint.h>