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

Change-Id: Ia6b4588546fda60ea2cd9ec581a017826cac9f66
diff --git a/mcord/mcord-control-plane/templates/mme.yaml b/mcord/mcord-control-plane/templates/mme.yaml
index 89e7309..9685c82 100644
--- a/mcord/mcord-control-plane/templates/mme.yaml
+++ b/mcord/mcord-control-plane/templates/mme.yaml
@@ -60,7 +60,7 @@
         app: mme
     spec:
       nodeSelector:
-        kubernetes.io/hostname: "node2"
+        kubernetes.io/hostname: "{{ .Values.mme_node_selector }}"
       terminationGracePeriodSeconds: 1
       initContainers:
       - name: init-mme