Make POD's node selector can configure in values.yaml

Change-Id: Ia6b4588546fda60ea2cd9ec581a017826cac9f66
diff --git a/mcord/mcord-control-plane/templates/hss.yaml b/mcord/mcord-control-plane/templates/hss.yaml
index d6d2f7e..9dd3918 100644
--- a/mcord/mcord-control-plane/templates/hss.yaml
+++ b/mcord/mcord-control-plane/templates/hss.yaml
@@ -46,7 +46,7 @@
         app: hss
     spec:
       nodeSelector:
-        kubernetes.io/hostname: "node3"
+        kubernetes.io/hostname: "{{ .Values.hss_node_selector }}"
       terminationGracePeriodSeconds: 1
       initContainers:
       - name: init-db