coreboot_table: Move VBOOT_VBNV support

The guard changes from (CHROMEOS && PC80_SYSTEM) to
VBOOT_VBNV_CMOS here.

Change-Id: I653285c04e864aa6a3494ba1400787fa184ba187
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50250
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/include/boot/coreboot_tables.h

@@ -41,4 +41,7 @@ void lb_table_add_serialno_from_vpd(struct lb_header *header);
 
 struct lb_record *lb_new_record(struct lb_header *header);
 
+/* Add VBOOT VBNV offsets. */
+void lb_table_add_vbnv_cmos(struct lb_header *header);
+
 #endif /* COREBOOT_TABLES_H */