drm/sun4i: Drop drm_vblank_cleanup

Again seems just cargo-culted ... It's not ordered against any
irq/vblank/modeset shutdown.

Cc: Maxime Ripard  <maxime.ripard@free-electrons.com>
Acked-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170524145212.27837-33-daniel.vetter@ffwll.ch

drivers/gpu/drm/sun4i/sun4i_drv.c

@@ -138,7 +138,6 @@ static int sun4i_drv_bind(struct device *dev)
 	sun4i_framebuffer_free(drm);
 cleanup_mode_config:
 	drm_mode_config_cleanup(drm);
-	drm_vblank_cleanup(drm);
 free_mem_region:
 	of_reserved_mem_device_release(dev);
 free_drm:
@@ -154,7 +153,6 @@ static void sun4i_drv_unbind(struct device *dev)
 	drm_kms_helper_poll_fini(drm);
 	sun4i_framebuffer_free(drm);
 	drm_mode_config_cleanup(drm);
-	drm_vblank_cleanup(drm);
 	of_reserved_mem_device_release(dev);
 	drm_dev_unref(drm);
 }