Fix Undo with added property field for additional lights (#2977)

* added property field additional lights rend mode

* updated changelog

Author: martint-unity

com.unity.render-pipelines.universal/CHANGELOG.md

@@ -44,6 +44,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed shadow cascade blend culling factor.
 - Removed Custom.meta which was causing warnings. [case 1314288](https://issuetracker.unity3d.com/issues/urp-warnings-about-missing-metadata-appear-after-installing)
 - Fixed a case where shadow fade was clipped too early.
+- Fixed undo issues for the additional light property on the UniversalRenderPipeline Asset. [case 1300367]
 
 ### Changed
 - Change Asset/Create/Shader/Universal Render Pipeline/Lit Shader Graph to Asset/Create/Shader Graph/URP/Lit Shader Graph

com.unity.render-pipelines.universal/Editor/UniversalRenderPipelineAssetEditor.cs

@@ -149,7 +149,6 @@ internal class Styles
 
         SerializedProperty m_ShaderVariantLogLevel;
 
-        LightRenderingMode selectedLightRenderingMode;
         SerializedProperty m_ColorGradingMode;
         SerializedProperty m_ColorGradingLutSize;
         SerializedProperty m_UseFastSRGBLinearConversion;
@@ -237,8 +236,6 @@ void OnEnable()
 
             m_UseAdaptivePerformance = serializedObject.FindProperty("m_UseAdaptivePerformance");
 
-            selectedLightRenderingMode = (LightRenderingMode)m_AdditionalLightsRenderingModeProp.intValue;
-
             string Key = "Universal_Shadow_Setting_Unit:UI_State";
             m_State = new EditorPrefBoolFlags<EditorUtils.Unit>(Key);
         }
@@ -326,8 +323,7 @@ void DrawLightingSettings()
                 EditorGUILayout.Space();
 
                 // Additional light
-                selectedLightRenderingMode = (LightRenderingMode)EditorGUILayout.EnumPopup(Styles.addditionalLightsRenderingModeText, selectedLightRenderingMode);
-                m_AdditionalLightsRenderingModeProp.intValue = (int)selectedLightRenderingMode;
+                EditorGUILayout.PropertyField(m_AdditionalLightsRenderingModeProp, Styles.addditionalLightsRenderingModeText);
                 EditorGUI.indentLevel++;
 
                 disableGroup = m_AdditionalLightsRenderingModeProp.intValue == (int)LightRenderingMode.Disabled;