[VOL-3091] configurable kafka topic

Make core-topic and adapter topics configurable in voltha-helm-charts
This is required to run multiple voltha stacks in a k8s deployment.

Also, read the kv_store_data_prefix via environment variable.
https://gerrit.opencord.org/#/c/19001/

Change-Id: I8fabda3ce70f1379f735796e6711f4282e57008a
diff --git a/voltha-adapter-openonu/values.yaml b/voltha-adapter-openonu/values.yaml
index 0edccb2..0097619 100644
--- a/voltha-adapter-openonu/values.yaml
+++ b/voltha-adapter-openonu/values.yaml
@@ -22,6 +22,10 @@
   image_tag: ~
   image_org: "voltha/"
   image_pullPolicy: "Always"
+  topics:
+    core_topic: "rwcore"
+    adapter_open_onu_topic: "brcm_openomci_onu"
+    adapter_open_olt_topic: "openolt"
 
 # Define connectivity to required services
 services: