bus: do not unref the added child bus on realize

When the parent bus removes the child property, it takes care of
removing the added reference, in object_finalize_child_property().
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20180531195119.22021-2-marcandre.lureau@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/core/bus.c

@@ -102,7 +102,6 @@ static void qbus_realize(BusState *bus, DeviceState *parent, const char *name)
         QLIST_INSERT_HEAD(&bus->parent->child_bus, bus, sibling);
         bus->parent->num_child_bus++;
         object_property_add_child(OBJECT(bus->parent), bus->name, OBJECT(bus), NULL);
-        object_unref(OBJECT(bus));
     } else if (bus != sysbus_get_default()) {
         /* TODO: once all bus devices are qdevified,
            only reset handler for main_system_bus should be registered here. */