pc: add "hotplug-memory-region-size" property to PC_MACHINE ... it will be used by acpi-build code and by unit tests Signed-off-by: Igor Mammedov <imammedo@redhat.com> Acked-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>