VOL-4284 simplify command line arg specification

Change-Id: Icc96dbf8ef1c06a4976c54fa53ce79f55f715e6a
diff --git a/rw_core/core/device/manager_test.go b/rw_core/core/device/manager_test.go
index 23968b5..1594b6e 100644
--- a/rw_core/core/device/manager_test.go
+++ b/rw_core/core/device/manager_test.go
@@ -79,7 +79,8 @@
 }
 
 func (dat *DATest) startCoreWithCustomICProxy(ctx context.Context, kmp kafka.InterContainerProxy) {
-	cfg := config.NewRWCoreFlags()
+	cfg := &config.RWCoreFlags{}
+	cfg.ParseCommandArguments([]string{})
 	cfg.CoreTopic = "rw_core"
 	cfg.EventTopic = "voltha.events"
 	cfg.DefaultRequestTimeout = dat.defaultTimeout