Update getting scoped storage CDM

Now that CDM-scoping was implemented, Getting scoped storage model
have to be updated.
This patch updates getting storage cluster data model.

Change-Id: Iefc22b54995aa8d2f3a7b3698575f6eb800d4289

watcher/decision_engine/model/collector/cinder.py

@@ -23,6 +23,7 @@ from watcher.decision_engine.model.collector import base
 from watcher.decision_engine.model import element
 from watcher.decision_engine.model import model_root
 from watcher.decision_engine.model.notification import cinder
+from watcher.decision_engine.scope import storage as storage_scope
 
 LOG = log.getLogger(__name__)
 
@@ -55,7 +56,9 @@ class CinderClusterDataModelCollector(base.BaseClusterDataModelCollector):
         ]
 
     def get_audit_scope_handler(self, audit_scope):
-        return None
+        self._audit_scope_handler = storage_scope.StorageScope(
+            audit_scope, self.config)
+        return self._audit_scope_handler
 
     def execute(self):
         """Build the storage cluster data model"""