drm/i915: use dev_priv directly in i915_driver_unload

Noticed while playing with coccinelle.

Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index d02c8de..46f1dec 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1867,7 +1867,7 @@
 		kmem_cache_destroy(dev_priv->slab);
 
 	pci_dev_put(dev_priv->bridge_dev);
-	kfree(dev->dev_private);
+	kfree(dev_priv);
 
 	return 0;
 }