Use voltha-rw-core v2.3.6

Change-Id: I13d42852039f7443686b295bc302552575881a0c
diff --git a/voltha/values.yaml b/voltha/values.yaml
index 8bc8421..f9773d1 100644
--- a/voltha/values.yaml
+++ b/voltha/values.yaml
@@ -103,5 +103,5 @@
   rw_core:
     registry: '{{ .Values.defaults.image_registry }}'
     repository: '{{ .Values.defaults.image_org }}voltha-rw-core'
-    tag: '{{- if hasKey .Values.defaults "image_tag" }}{{- if .Values.defaults.image_tag }}{{ .Values.defaults.image_tag }}{{- else }}2.3.5{{- end }}{{- else }}2.3.5{{- end }}'
+    tag: '{{- if hasKey .Values.defaults "image_tag" }}{{- if .Values.defaults.image_tag }}{{ .Values.defaults.image_tag }}{{- else }}2.3.6{{- end }}{{- else }}2.3.6{{- end }}'
     pullPolicy: '{{ .Values.defaults.image_pullPolicy }}'