Remove get_namespace() from l2gw extensions

This method was removed from all extensions
per I3c406910991c33cf959c5345d76153eabe3ace2d

Change-Id: Idc357dedfac1d5a9376dee5629893f7db608bdac
Closes-bug: 1477794

networking_l2gw/extensions/l2gateway.py

@@ -61,11 +61,6 @@ class L2gateway(extensions.ExtensionDescriptor):
     def get_description(cls):
         return "Connects Neutron networks with external networks at layer 2."
 
-    @classmethod
-    def get_namespace(cls):
-        return "https://review.openstack.org/#/c/144173/3/specs/kilo/"
-    "l2-gateway-api.rst"
-
     @classmethod
     def get_updated(cls):
         return "2015-01-01T00:00:00-00:00"

networking_l2gw/extensions/l2gatewayconnection.py

@@ -58,11 +58,6 @@ class L2gatewayconnection(extensions.ExtensionDescriptor):
     def get_description(cls):
         return "Connects Neutron networks with external networks at layer 2."
 
-    @classmethod
-    def get_namespace(cls):
-        return "https://review.openstack.org/#/c/144173/3/specs/kilo/"
-        "l2-gateway-api.rst"
-
     @classmethod
     def get_updated(cls):
         return "2014-01-01T00:00:00-00:00"