AETHER-761 Add support of private image registry with auth enabled

Change-Id: I25e804570357c513bfd1822ab9d971c7ed1c5405
diff --git a/omec/omec-user-plane/templates/statefulset-upf.yaml b/omec/omec-user-plane/templates/statefulset-upf.yaml
index fd63696..59187be 100644
--- a/omec/omec-user-plane/templates/statefulset-upf.yaml
+++ b/omec/omec-user-plane/templates/statefulset-upf.yaml
@@ -51,6 +51,10 @@
       nodeSelector:
         {{ .Values.nodeSelectors.upf.label }}: {{ .Values.nodeSelectors.upf.value }}
     {{- end }}
+    {{- if .Values.images.credentials }}
+      imagePullSecrets:
+        - name: {{ .Release.Name }}.registry
+    {{- end }}
       initContainers:
       - name: bess-init
         image: {{ .Values.images.tags.bess | quote }}