object_initialize() leaves the object with a refcount of 1.
object_property_add_child() adds its own reference which is dropped
again when the property is deleted.
The upshot of this is that we always have a refcount >= 1. Upon hot
unplug the virtio-blk child is not finalized!
Drop our reference after the child property has been added to the
parent.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>