HDRenderPipeline: Update UI to not display metal mask when in specular color mode with Lit

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Editor/LitUI.cs

             public static GUIContent smoothnessText = new GUIContent("Smoothness", "Smoothness scale factor");
             public static GUIContent smoothnessRemappingText = new GUIContent("Smoothness Remapping", "Smoothness remapping");
             public static GUIContent maskMapSText = new GUIContent("Mask Map - M(R), AO(G), D(B), S(A)", "Mask map");
+            public static GUIContent maskMapSpecularText = new GUIContent("Mask Map - AO(G), D(B), S(A)", "Mask map");            
 
             public static GUIContent normalMapSpaceText = new GUIContent("Normal Map space", "");
             public static GUIContent normalMapText = new GUIContent("Normal Map", "Normal Map (BC7/BC5/DXT5(nm))");
                 }
             }
 
-            m_MaterialEditor.TexturePropertySingleLine(Styles.maskMapSText, maskMap[layerIndex]);
+            m_MaterialEditor.TexturePropertySingleLine((Lit.MaterialId)materialID.floatValue == Lit.MaterialId.LitSpecular ? Styles.maskMapSpecularText : Styles.maskMapSText, maskMap[layerIndex]);
 
             m_MaterialEditor.ShaderProperty(normalMapSpace[layerIndex], Styles.normalMapSpaceText);