Fix create secret commands

Regression bug introduced in https://github.com/fluxcd/flux2/pull/788

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

cmd/flux/create_secret.go

@@ -51,6 +51,8 @@ func makeSecret(name string) (corev1.Secret, error) {
 			Namespace: rootArgs.namespace,
 			Labels:    secretLabels,
 		},
+		StringData: map[string]string{},
+		Data:       nil,
 	}, nil
 }