Fix wrong variable reference in Grafana & Pulsar Manager port (#41)

### Motivation

PR #37 updated the location of the ports in the default values yaml. This causes a null pointer exception when rendering this helm chart.

### Modifications

Fix variable reference

charts/pulsar/templates/grafana-deployment.yaml

@@ -61,7 +61,7 @@ spec:
       {{- end }}
         ports:
         - name: server
-          containerPort: {{ .Values.grafana.port }}
+          containerPort: {{ .Values.grafana.service.targetPort }}
         env:
         # for supporting apachepulsar/pulsar-grafana
         - name: PROMETHEUS_URL

charts/pulsar/templates/pulsar-manager-deployment.yaml

@@ -58,7 +58,7 @@ spec:
 {{ toYaml .Values.pulsar_manager.resources | indent 12 }}
         {{- end }}
           ports:
-          - containerPort: {{ .Values.pulsar_manager.port }}
+          - containerPort: {{ .Values.pulsar_manager.service.targetPort }}
           volumeMounts:
           - name: pulsar-manager-data
             mountPath: /data