drm: mark dma setup/teardown as legacy systems

And hide the checks a bit better. This was already disallowed for
modesetting drivers, so no functinal change here.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 743b24d..5b949a7 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -205,9 +205,7 @@
 		kfree(vma);
 	}
 
-	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
-	    !drm_core_check_feature(dev, DRIVER_MODESET))
-		drm_dma_takedown(dev);
+	drm_legacy_dma_takedown(dev);
 
 	dev->dev_mapping = NULL;
 	mutex_unlock(&dev->struct_mutex);