drm/vram_helper: call explicit mm takedown

Reviewed-by: NThomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200804025632.3868079-30-airlied@gmail.com

drivers/gpu/drm/drm_gem_vram_helper.c

@@ -1127,6 +1127,7 @@ static int drm_vram_mm_init(struct drm_vram_mm *vmm, struct drm_device *dev,
 
 static void drm_vram_mm_cleanup(struct drm_vram_mm *vmm)
 {
+	ttm_range_man_fini(&vmm->bdev, &vmm->bdev.man[TTM_PL_VRAM]);
 	ttm_bo_device_release(&vmm->bdev);
 }