remove trailing comma for linter

The linter sees the trailing comma after the function call as building
a tuple without wrapping it in parens. That doesn't seem to be the
intent (it looks like a typo), so remove the comma.

Change-Id: Ie3e051c43d68d09716fc0a4506ed111908730280
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

neutron/services/l3_router/service_providers/driver_controller.py

@@ -173,7 +173,7 @@ class DriverController(object):
                 registry.publish(
                     resources.ROUTER_CONTROLLER,
                     events.PRECOMMIT_ADD_ASSOCIATION,
-                    trigger, payload=payload),
+                    trigger, payload=payload)
 
     def get_provider_for_router(self, context, router_id):
         """Return the provider driver handle for a router id."""