smbios: add smbios_add_usr_blob_size() helper

it will be used by follow up patch when legacy handling
is moved out into a separate file.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Message-Id: <20240314152302.2324164-10-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
1 file changed