efl_ui_image: unload file before memfile_set

Summary:
If memfile_set does not remove prev file information, it is not possilbe to
load image using the same file information after memefile_set.

It means that below line 3 does not work because the same file information
remains for Efl.Ui.Image_Legacy.

1 |  elm_image_file_set(obj, "1.jpg", NULL)
2 |  elm_image_memfile_set(obj, img, size, "jpg", NULL)
3 |  elm_image_file_set(obj, "1.jpg", NULL)

This patch removes line calling _efl_ui_image_file_set_do becasue it is called
in efl_file_unload > _efl_ui_image_efl_file_unload.

Test Plan:
[Sample Code]
{F3848315}

[Reproduce Step]
1. File2
2. Memfile
3. File2

Reviewers: Hermet, jsuya

Reviewed By: Hermet

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D11392

src/lib/elementary/efl_ui_image.c

@@ -2415,7 +2415,7 @@ elm_image_memfile_set(Evas_Object *obj, const void *img, size_t size, const char
    EFL_UI_IMAGE_CHECK(obj) EINA_FALSE;
    EFL_UI_IMAGE_DATA_GET(obj, sd);
 
-   _efl_ui_image_file_set_do(obj);
+   efl_file_unload(obj);
 
    evas_object_image_memfile_set
      (sd->img, (void *)img, size, (char *)format, (char *)key);