sb/intel: Factor out soc_fill_gnvs()

Name the common part of GNVS initialisation as soc_fill_gnvs().
It is also moved before the call to acpi_create_gnvs(), which
followup will rename to mainbord_fill_gnvs() to reflect that
implementation is under mb/.

Change-Id: Ic4cf1548b65a86212d6e45d460fcd23bb8036365
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48706
Reviewed-by: Lance Zhao
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/acpi/acpi_gnvs.h

@@ -34,4 +34,6 @@ void southbridge_inject_dsdt(const struct device *device);
 void acpi_create_gnvs(struct global_nvs *gnvs);
 void acpi_init_gnvs(struct global_nvs *gnvs);
 
+void soc_fill_gnvs(struct global_nvs *gnvs);
+
 #endif