ACPI: Refactor ChromeOS specific ACPI GNVS

The layout of GNVS has expectation for a fixed size
array for chromeos_acpi_t. This allows us to reduce
the exposure of <chromeos/gnvs.h>.

If chromeos_acpi_t was the last entry in struct global_nvs
padding at the end is also removed.

If device_nvs_t exists, place a properly sized reserve for
chromeos_acpi_t in the middle.

Allocation from cbmem is adjusted such that it matches exactly
the OperationRegion size defined inside the ASL.

Change-Id: If234075e11335ce958ce136dd3fe162f7e5afdf7
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48788
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/acpi/acpi_gnvs.h

@@ -8,14 +8,13 @@
 void *acpi_get_gnvs(void);
 void *gnvs_get_or_create(void);
 
-void gnvs_assign_chromeos(void);
+void gnvs_assign_chromeos(void *gnvs_section);
 void gnvs_set_ecfw_rw(void);
 
 /* Platform code must implement these. */
 struct global_nvs;
 size_t gnvs_size_of_array(void);
 uint32_t *gnvs_cbmc_ptr(struct global_nvs *gnvs);
-void *gnvs_chromeos_ptr(struct global_nvs *gnvs);
 
 /*
  * These functions populate the gnvs structure in acpi table.