acpi: cphp: Force switch to modern cpu hotplug if APIC ID > 254

Switch to modern cpu hotplug at machine startup time if
a cpu present at boot has apic-id in range unsupported
by legacy cpu hotplug interface (i.e. > 254), to avoid
killing QEMU from legacy cpu hotplug code with error:
   "acpi: invalid cpu id: #apic-id#"

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
