smbios: get rid of smbios_legacy global

smbios: get rid of smbios_legacy global

clean up smbios_set_defaults() which is reused by legacy
and non legacy machines from being aware of 'legacy' notion
and need to turn it off. And push legacy handling up to
PC machine code where it's relevant.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Acked-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
Message-Id: <20240314152302.2324164-7-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>