core: engine-config didn't show HotUnplugCpuSupported value

add HotUnplugCpuSupported to vdc_options so engine-config utility could
see the default value as well

Change-Id: Ief7fe91d9947e778588ae2b73684ead68df8dc6b
Bug-Url: https://bugzilla.redhat.com/1100430
Signed-off-by: Roy Golan <rgolan@redhat.com>