Fix T46405: Cycles point density missing update when modifying source object

Referenced by issue #46405, Point density textures. When using vertices as source, the viewport preview render does not update when adding a modifier or changing modifier settings.

intern/cycles/blender/blender_shader.cpp

@@ -767,7 +767,7 @@ static ShaderNode *add_node(Scene *scene,
 			        point_density->filename,
 			        point_density->builtin_data,
 			        point_density->interpolation,
-			        EXTENSION_REPEAT);
+			        EXTENSION_CLIP);
 		}
 		node = point_density;
 	}