Remove Neutron NEC plugin completely

override-defaults mechanism allows us to define
s_neutron_plugin_security_group before loading lib/neutron,
and we no longer need to have a plugin-specific file in
the master DevStack repository.

Change-Id: I78a4e05fa72b1dd545b8d9e97a8fd8fdbf23739c
Depends-On: Id6765245459c1aff3aab27dbc60d320ce2951b38

lib/neutron_plugins/nec

@@ -1,10 +0,0 @@
-#!/bin/bash
-
-# This file is needed so Q_PLUGIN=nec will work.
-
-# FIXME(amotoki): This function should not be here, but unfortunately
-# devstack calls it before the external plugins are fetched
-function has_neutron_plugin_security_group {
-    # 0 means True here
-    return 0
-}