Using images for VOLTHA-2.6 release

Change-Id: I7d9d34948214caff390f150c5e48e3427b225520
diff --git a/voltha-adapter-openonu/values.yaml b/voltha-adapter-openonu/values.yaml
index a7722b8..c324e76 100644
--- a/voltha-adapter-openonu/values.yaml
+++ b/voltha-adapter-openonu/values.yaml
@@ -82,5 +82,5 @@
   adapter_open_onu_go:
     registry: '{{ .Values.defaults.image_registry }}'
     repository: '{{ .Values.defaults.image_org }}voltha-openonu-adapter-go'
-    tag: '{{- if hasKey .Values.defaults "image_tag" }}{{- if .Values.defaults.image_tag }}{{ .Values.defaults.image_tag }}{{- else }}master{{- end }}{{- else }}master{{- end }}'
+    tag: '{{- if hasKey .Values.defaults "image_tag" }}{{- if .Values.defaults.image_tag }}{{ .Values.defaults.image_tag }}{{- else }}0.1.15{{- end }}{{- else }}0.1.15{{- end }}'
     pullPolicy: '{{ .Values.defaults.image_pullPolicy }}'