Avoid the API call to update pod if nothing is changed

Signed-off-by: Dave Chen <dave.chen@arm.com>

pkg/scheduler/util/utils.go

@@ -133,6 +133,11 @@ func PatchPod(cs kubernetes.Interface, old *v1.Pod, new *v1.Pod) error {
 	if err != nil {
 		return fmt.Errorf("failed to create merge patch for pod %q/%q: %v", old.Namespace, old.Name, err)
 	}
+
+	if "{}" == string(patchBytes) {
+		return nil
+	}
+
 	_, err = cs.CoreV1().Pods(old.Namespace).Patch(context.TODO(), old.Name, types.StrategicMergePatchType, patchBytes, metav1.PatchOptions{}, "status")
 	return err
 }