drm/gma500: Do not clear framebuffer GEM objects during cleanup

Gma500 unnecessarily clears the framebuffer's GEM-object pointer
before calling drm_framebuffer_cleanup(). Remove this code to make
gma500 consistent with the rest of the drivers.

The change is cosmetic, as drm_framebuffer_cleanup() does not
touch the object pointer on gma500.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Acked-by: Patrik Jakobsson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/gma500/fbdev.c

···
 	drm_fb_helper_fini(fb_helper);
 
 	drm_framebuffer_unregister_private(fb);
-	fb->obj[0] = NULL;
 	drm_framebuffer_cleanup(fb);
 	kfree(fb);
 
···
 
 err_drm_framebuffer_unregister_private:
 	drm_framebuffer_unregister_private(fb);
-	fb->obj[0] = NULL;
 	drm_framebuffer_cleanup(fb);
 	kfree(fb);
 err_drm_gem_object_put: