ACPI: Clean up GNVS initialisation

With the common <soc/nvs.h> approach platform does not
need to implement the common accessors or sizeof() function.

Change-Id: I1050a252f765c763c1ae2d1610cbfb0d973ba026
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49793
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/lib/hardwaremain.c

@@ -450,7 +450,7 @@ void main(void)
 
 	/* Initialise GNVS early. */
 	if (CONFIG(ACPI_SOC_NVS))
-		gnvs_get_or_create();
+		acpi_create_gnvs();
 
 	/* Schedule the static boot state entries. */
 	boot_state_schedule_static_entries();