Add an ability to use existing configMap for Kustomize support

Change-Id: Id331042cf363d40ec3d8c0dfd0dfce90fe2dc0fb
diff --git a/omec/5g-control-plane/values.yaml b/omec/5g-control-plane/values.yaml
index 476caae..49432f8 100644
--- a/omec/5g-control-plane/values.yaml
+++ b/omec/5g-control-plane/values.yaml
@@ -100,6 +100,7 @@
   #replicaCount: 3
 
 config:
+  useExistingConfigMap: false
   coreDump:
     enabled: false
     path: /tmp/coredump