Kill radvd when stopping neutron-l3 service

When stopping neutron-l3 service, radvd should be
stopped.

Change-Id: I46416c1df3a4da66e863a16baeb73886e110d447
Closes-Bug: #1535661
diff --git a/lib/neutron-legacy b/lib/neutron-legacy
index 9497a23..a148971 100644
--- a/lib/neutron-legacy
+++ b/lib/neutron-legacy
@@ -764,7 +764,11 @@
     fi
 
     stop_process q-svc
-    stop_process q-l3
+
+    if is_service_enabled q-l3; then
+        sudo pkill -f "radvd -C $DATA_DIR/neutron/ra"
+        stop_process q-l3
+    fi
 
     if is_service_enabled q-meta; then
         sudo pkill -9 -f neutron-ns-metadata-proxy || :