VOL-1797 - fix helm lint issues

Change-Id: I74ccff1f7f431e05fc3963d0707382f478a010f0
diff --git a/voltha/templates/rw-core.yaml b/voltha/templates/rw-core.yaml
index ee2ddd0..28e5f22 100644
--- a/voltha/templates/rw-core.yaml
+++ b/voltha/templates/rw-core.yaml
@@ -14,7 +14,7 @@
 
 {{- $root := . -}}
 {{- $count := mul .Values.replicas.rw_core 2 | int }}
-{{- $tag := tpl .Values.images.rw_core.tag . }}
+{{- $tag := tpl ( tpl .Values.images.rw_core.tag . ) . }}
 {{- $repository := tpl .Values.images.rw_core.repository . }}
 {{- $registry := tpl .Values.images.rw_core.registry . }}
 {{- $pullpolicy := tpl .Values.images.rw_core.pullPolicy . }}