remove unused methods in common_db_mixin

The following methods are no longer used in CommonDbMixin:
- register_dict_extend_funcs
- _apply_filters_to_query
- _filter_non_model_columns

This patch removes them from neutron.

NeutronLibImpact

Change-Id: Ic7042cdcb29e95cc3a13292819d77abc3971fe8a

neutron/db/common_db_mixin.py

@@ -14,7 +14,6 @@
 #    under the License.
 
 from neutron_lib.db import model_query
-from neutron_lib.db import resource_extend
 from neutron_lib.db import utils as db_utils
 
 
@@ -22,10 +21,6 @@ from neutron_lib.db import utils as db_utils
 class CommonDbMixin(object):
     """Deprecated."""
 
-    @staticmethod
-    def register_dict_extend_funcs(resource, funcs):
-        resource_extend.register_funcs(resource, funcs)
-
     @staticmethod
     def _model_query(context, model):
         return model_query.query_with_hooks(context, model)
@@ -38,10 +33,6 @@ class CommonDbMixin(object):
     def _get_by_id(context, model, id):
         return model_query.get_by_id(context, model, id)
 
-    @staticmethod
-    def _apply_filters_to_query(query, model, filters, context=None):
-        return model_query.apply_filters(query, model, filters, context)
-
     @staticmethod
     def _get_collection_query(context, model,
                               filters=None, sorts=None,
@@ -69,7 +60,3 @@ class CommonDbMixin(object):
     # TODO(HenryG): Remove this when available in neutron-lib
     def _get_marker_obj(self, context, resource, limit, marker):
         return db_utils.get_marker_obj(self, context, resource, limit, marker)
-
-    @staticmethod
-    def _filter_non_model_columns(data, model):
-        return db_utils.filter_non_model_columns(data, model)