drm/i915: Move the gtt mm takedown to cleanup

Our VM code already has a cleanup function, and this is a nice place to
put the drm_mm_takedown. This should have no functional impact, it just
leaves the unload function a bit cleaer, and is more logical IMO
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1777,7 +1777,6 @@ int i915_driver_unload(struct drm_device *dev)
 
 	list_del(&dev_priv->gtt.base.global_link);
 	WARN_ON(!list_empty(&dev_priv->vm_list));
-	drm_mm_takedown(&dev_priv->gtt.base.mm);
 
 	drm_vblank_cleanup(dev);
 

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1411,6 +1411,8 @@ static void gen6_gmch_remove(struct i915_address_space *vm)
 {
 
 	struct i915_gtt *gtt = container_of(vm, struct i915_gtt, base);
+
+	drm_mm_takedown(&vm->mm);
 	iounmap(gtt->gsm);
 	teardown_scratch_page(vm->dev);
 }