drm/exynos: Stop using drm_framebuffer_unregister_private

This is the deprecated function for when you embedded the framebuffer
somewhere else (which breaks refcounting). But exynos is using
drm_framebuffer_remove and a free-standing fb, so this is rendundant.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: NInki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

@@ -270,10 +270,8 @@ static void exynos_drm_fbdev_destroy(struct drm_device *dev,
 	/* release drm framebuffer and real buffer */
 	if (fb_helper->fb && fb_helper->fb->funcs) {
 		fb = fb_helper->fb;
-		if (fb) {
-			drm_framebuffer_unregister_private(fb);
+		if (fb)
 			drm_framebuffer_remove(fb);
-		}
 	}
 
 	drm_fb_helper_unregister_fbi(fb_helper);