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

Change-Id: I5027a1f2cee3246c695c5dab2c6823ab1294facd
diff --git a/voltha/values.yaml b/voltha/values.yaml
index 86ef37e..8d288a7 100644
--- a/voltha/values.yaml
+++ b/voltha/values.yaml
@@ -22,7 +22,7 @@
 # The following are the default values used for every container in the
 # template.
 defaults:
-  log_level: "ERROR"
+  log_level: "WARN"
   image_registry: ''
   image_org: "voltha/"
   image_tag: ~