ACPI: Drop redundant CBMEM_ID_ACPI_GNVS allocations

Allocation now happens prior to device enumeration. The
step cbmem_add() is a no-op here, if reached for some
boards. The memset() here is also redundant and becomes
harmful with followup works, as it would wipe out the
CBMEM console and ChromeOS related fields without them
being set again.

Change-Id: I9b2625af15cae90b9c1eb601e606d0430336609f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48701
Reviewed-by: Lance Zhao
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/acpi/gnvs.c

@@ -29,12 +29,7 @@ static void gnvs_assign_cbmc(void)
 		*gnvs_cbmc = (uintptr_t)cbmem_find(CBMEM_ID_CONSOLE);
 }
 
-/* Platforms that implement GNVS will need to implement these. */
-__weak size_t gnvs_size_of_array(void)
-{
-	return 0;
-}
-
+/* Needs implementation in platform code. */
 __weak uint32_t *gnvs_cbmc_ptr(struct global_nvs *gnvs_)
 {
 	return NULL;