it adds CPU objects to DSDT with _STA method
and QEMU side of CPU hotplug interface initialization
with registers sufficient to handle _STA requests,
including necessary hotplug callbacks in piix4,ich9 code.

Hot-(un)plug hw/acpi parts will be added by
corresponding follow up patches.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>