cleanup, sensible default override capability, openolt and onu support

Change-Id: I8e542dfe40947324c44a19605dde23d0e5198afe
diff --git a/voltha-adapter-simulated/values.yaml b/voltha-adapter-simulated/values.yaml
index 2dd877f..cc774c7 100644
--- a/voltha-adapter-simulated/values.yaml
+++ b/voltha-adapter-simulated/values.yaml
@@ -13,8 +13,12 @@
 # limitations under the License.
 
 ---
-# Globally define a registry
-registry: ''
+# Default overrides
+defaults:
+  image_registry:
+  image_tag:
+  image_org:
+  image_pullPolicy:
 
 # Define connectivity to required services
 services:
@@ -39,16 +43,13 @@
 
 images:
   adapter_simulated_olt:
-    repository: 'volthacore/voltha-adapter-simulated-olt'
-    tag: '{{ .Chart.AppVersion }}'
-    pullPolicy: 'Always'
+    registry: '{{ .Values.defaults.image_registry | default "" }}'
+    repository: '{{ .Values.defaults.image_org | default "voltha/" }}voltha-adapter-simulated-olt'
+    tag: '{{ .Values.defaults.image_tag | default .Chart.AppVersion }}'
+    pullPolicy: '{{ .Values.defaults.image_pullPolicy | default "Always" }}'
 
   adapter_simulated_onu:
-    repository: 'volthacore/voltha-adapter-simulated-onu'
-    tag: '{{ .Chart.AppVersion }}'
-    pullPolicy: 'Always'
-
-  ponsim:
-    repository: 'volthacore/voltha-ponsim'
-    tag: '{{ .Chart.AppVersion }}'
-    pullPolicy: 'Always'
+    registry: '{{ .Values.defaults.image_registry | default "" }}'
+    repository: '{{ .Values.defaults.image_org | default "voltha/" }}voltha-adapter-simulated-onu'
+    tag: '{{ .Values.defaults.image_tag | default .Chart.AppVersion }}'
+    pullPolicy: '{{ .Values.defaults.image_pullPolicy | default "Always" }}'