virtio/s390: use dev_to_virtio

Use dev_to_virtio() instead of open-coding it.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Message-Id: <912bf59bd3a48f2d4d4994681e898dc084fe29d3.1451484163.git.geliangtang@163.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index bf2d130..46b110a1 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -945,8 +945,7 @@
 
 static void virtio_ccw_release_dev(struct device *_d)
 {
-	struct virtio_device *dev = container_of(_d, struct virtio_device,
-						 dev);
+	struct virtio_device *dev = dev_to_virtio(_d);
 	struct virtio_ccw_device *vcdev = to_vc_device(dev);
 
 	kfree(vcdev->status);