Updating nem monitoring chart to the standard decl format

Change-Id: I29a11c5907702d81fc8fda3655d041d29246014f
diff --git a/nem-monitoring/values.yaml b/nem-monitoring/values.yaml
index 886e502..1719a3e 100644
--- a/nem-monitoring/values.yaml
+++ b/nem-monitoring/values.yaml
@@ -13,10 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-nem_voltha_kpi_exporter_image: "opencord/kafka-topic-exporter:latest"
+global:
+  registry: ''
+
+images:
+  voltha_kpi_exporter:
+    repository: 'opencord/kafka-topic-exporter'
+    tag: 'latest'
+    pullPolicy: 'Always'
+
 nem_voltha_kpi_exporter_nodePort: 31080
 nem_voltha_kpi_exporter_replicas: 2
-imagePullPolicy: "Always"
+
 args:
   voltha_kpi_broker: cord-kafka:9092
 
@@ -210,4 +218,4 @@
           type: prometheus
           url: http://nem-monitoring-prometheus-server.default.svc.cluster.local
           access: proxy
-          isDefault: true
\ No newline at end of file
+          isDefault: true