Exposing log level in the helm-chart for single rw-core and openolt-adapter

Change-Id: I5027a1f2cee3246c695c5dab2c6823ab1294facd
diff --git a/voltha-adapter-openonu/values.yaml b/voltha-adapter-openonu/values.yaml
index b1d02dc..eb4bbfe 100644
--- a/voltha-adapter-openonu/values.yaml
+++ b/voltha-adapter-openonu/values.yaml
@@ -15,6 +15,7 @@
 ---
 # Default overrides
 defaults:
+  log_level: "WARN"
   image_registry: ""
   image_tag: ~
   image_org: "voltha/"
@@ -40,7 +41,7 @@
   adapter_open_onu: 1
 
 adapter_open_onu:
-  log_level: INFO
+  log_level: '{{ .Values.defaults.log_level }}'
 
 images:
   adapter_open_onu: