Fixed issue in handling annotations in SecurityGroupKM

Since the annotations value are sent in the second update,
it is possible to get the none value for the first update.
using empty dict on those cases would fix the issue.

Change-Id: I35ca83fccaaa86f43779a085273231b2685885d3
Closes-bug: #1677439

src/container/kube-manager/kube_manager/vnc/config_db.py

@@ -726,7 +726,7 @@ def update(self, obj=None):
         self.name = obj['fq_name'][-1]
         self.fq_name = obj['fq_name']
         self.build_fq_name_to_uuid(self.uuid, obj)
-        self.annotations = obj.get('annotations', None)
+        self.annotations = obj.get('annotations', {})
         for kvp in self.annotations.get('key_value_pair', []):
             if kvp.get('key') == 'namespace':
                 self.namespace = kvp.get('value')