Avoid ListPool from ambiguous reference

This could happens if Core RP Library package is installed

Author: lawwong

Assets/HTC.UnityPlugin/ViveInputUtility/Scripts/Editor/VIUSettingsEditor.cs

@@ -9,11 +9,12 @@
 using System.Reflection;
 using UnityEditor;
 using UnityEngine;
-using UnityEngine.Rendering;
 #if UNITY_2018_1_OR_NEWER
 using UnityEditor.PackageManager;
 using UnityEditor.PackageManager.Requests;
 #endif
+using GraphicsDeviceType = UnityEngine.Rendering.GraphicsDeviceType;
+
 
 namespace HTC.UnityPlugin.Vive
 {