Fix destroy DBReferenceError in driver_device.py

The error info as follows：

Cannot delete or update a parent row: a foreign key constraint fails
(`cyborg`.`attach_handles`, CONSTRAINT `attach_handles_ibfk_2` FOREIGN
KEY (`cpid_id`) REFERENCES `controlpath_ids` (`id`)

Change-Id: I1fcfb367dba520be98e792559a463b7f9804198d

cyborg/objects/driver_objects/driver_device.py

@@ -79,14 +79,14 @@ class DriverDevice(base.DriverObjectBase,
         delete the internal layer objects."""
         # get dev_obj_list from hostname
         device_obj = self.get_device_obj(context, host)
+        # delete deployable_list first.
+        for driver_deployable in self.deployable_list:
+            driver_deployable.destroy(context, device_obj.id)
         if hasattr(self.controlpath_id, 'cpid_info'):
             cpid_obj = ControlpathID.get_by_device_id_cpidinfo(
                 context, device_obj.id, self.controlpath_id.cpid_info)
             # delete controlpath_id
             cpid_obj.destroy(context)
-        # delete deployable_list first.
-        for driver_deployable in self.deployable_list:
-            driver_deployable.destroy(context, device_obj.id)
         # delete the device
         device_obj.destroy(context)