Removed distortion only for lit shader

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.shader

 
         _DistortionVectorMap("DistortionVectorMap", 2D) = "black" {}
         [ToggleOff] _DistortionEnable("Enable Distortion", Float) = 0.0
-        [ToggleOff] _DistortionOnly("Distortion Only", Float) = 0.0
         [ToggleOff] _DistortionDepthTest("Distortion Depth Test Enable", Float) = 0.0
         [Enum(Add, 0, Multiply, 1)] _DistortionBlendMode("Distortion Blend Mode", Int) = 0
         [HideInInspector] _DistortionSrcBlend("Distortion Blend Src", Int) = 0

ScriptableRenderPipeline/HDRenderPipeline/Material/Unlit/Editor/BaseUnlitUI.cs

                 {
                     EditorGUI.indentLevel++;
                     m_MaterialEditor.ShaderProperty(distortionBlendMode, StylesBaseUnlit.distortionBlendModeText);
-                    m_MaterialEditor.ShaderProperty(distortionOnly, StylesBaseUnlit.distortionOnlyText);
+                    if (distortionOnly != null)
+                        m_MaterialEditor.ShaderProperty(distortionOnly, StylesBaseUnlit.distortionOnlyText);
                     m_MaterialEditor.ShaderProperty(distortionDepthTest, StylesBaseUnlit.distortionDepthTestText);
 
                     EditorGUI.indentLevel++;