[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/templates/core-deploy.yaml b/voltha/templates/core-deploy.yaml
index 1a805ec..6ce8406 100644
--- a/voltha/templates/core-deploy.yaml
+++ b/voltha/templates/core-deploy.yaml
@@ -74,6 +74,8 @@
               valueFrom:
                 fieldRef:
                   fieldPath: metadata.labels['app.kubernetes.io/name']
+            - name: KV_STORE_DATAPATH_PREFIX
+              value: {{ .Values.defaults.kv_store_data_prefix }}
           args:
             - "/app/rw_core"
             - "-kv_store_type=etcd"
@@ -86,9 +88,7 @@
             - "-kafka_adapter_port={{ .Values.services.kafka.adapter.port }}"
             - "-kafka_cluster_host={{ .Values.services.kafka.cluster.service }}"
             - "-kafka_cluster_port={{ .Values.services.kafka.cluster.port }}"
-            - "-rw_core_topic=rwcore"
-            - "-core_pair_topic=core-pair-1"
-            - "-kv_store_data_prefix=service/voltha"
+            - "-rw_core_topic={{ .Values.defaults.topics.core_topic }}"
             - "-in_competing_mode=false"
             - "-core_timeout=10s"
             - "-timeout_long_request=10s"