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/include/acpi/acpi_gnvs.h

@@ -5,22 +5,22 @@
 
 #include <types.h>
 
+void acpi_create_gnvs(void);
+#if CONFIG(ACPI_SOC_NVS)
 void *acpi_get_gnvs(void);
-void *gnvs_get_or_create(void);
+#else
+static inline void *acpi_get_gnvs(void) { return NULL; }
+#endif
 
 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);
-
 /*
  * These functions populate the gnvs structure in acpi table.
  * Defined as weak in common acpi as gnvs structure definition is
  * chipset specific.
  */
+struct global_nvs;
 void soc_fill_gnvs(struct global_nvs *gnvs);
 void mainboard_fill_gnvs(struct global_nvs *gnvs);