virtio-net: fix virtio-net child refcount in transports
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-net child is not finalized!
Drop our reference after the child property has been added to the
parent.
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>