ACPI: Refactor use of global and device NVS

After ChromeOS NVS was moved to a separate allocation and the use
of multiple OperationRegions, maintaining the fixed offsets is not
necessary.

Use actual structure size for OperationRegions, but align the
allocations to 8 bytes or sizeof(uint64_t).

Change-Id: I9c73b7c44d234af42c571b23187b924ca2c3894a
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51639
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/acpi/acpi_gnvs.h

@@ -8,6 +8,8 @@
 struct global_nvs;
 
 void acpi_create_gnvs(void);
+size_t size_of_dnvs(void);
+
 #if CONFIG(ACPI_SOC_NVS)
 void *acpi_get_gnvs(void);
 void *acpi_get_device_nvs(void);