introduce check_onu_exist_on_discovery flag for openolt adapter

Change-Id: If391627d6823fd416417672e6b8bf4d91bd00c0e
diff --git a/voltha-adapter-openolt/templates/openolt-deploy.yaml b/voltha-adapter-openolt/templates/openolt-deploy.yaml
index 9010d7c..a9b8fad 100644
--- a/voltha-adapter-openolt/templates/openolt-deploy.yaml
+++ b/voltha-adapter-openolt/templates/openolt-deploy.yaml
@@ -135,6 +135,7 @@
             - "--omcc_encryption={{ .Values.global.omcc_encryption }}"
             - "--enable_onu_stats={{ .Values.global.enable_onu_stats }}"
             - "--enable_gem_stats={{ .Values.global.enable_gem_stats }}"
+            - "--check_onu_exist_on_discovery={{ tpl .Values.adapter_open_olt.check_onu_exist_on_discovery . }}"
           {{- if .Values.securityContext.enabled }}
           securityContext:
             allowPrivilegeEscalation: false