Fix recent typo in mirror object alpha setting

ref 6a04bfb0ff

src/bin/e_comp_object.c

@@ -4106,7 +4106,7 @@ e_comp_object_dirty(Evas_Object *obj)
         //evas_object_image_border_set(o, bx, by, bxx, byy);
         //evas_object_image_border_center_fill_set(o, EVAS_BORDER_FILL_SOLID);
         evas_object_image_pixels_dirty_set(o, dirty);
-        evas_object_image_alpha_set(obj, alpha);
+        evas_object_image_alpha_set(o, alpha);
         if (!dirty)
           evas_object_image_data_set(o, NULL);
         evas_object_image_size_set(o, w, h);