um: Kill directly reference of netdev->priv

Simply replace netdev->priv with netdev_priv().

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/um/drivers/slip_kern.c b/arch/um/drivers/slip_kern.c
index d19faec..5ec1756 100644
--- a/arch/um/drivers/slip_kern.c
+++ b/arch/um/drivers/slip_kern.c
@@ -19,7 +19,7 @@
 	struct slip_data *spri;
 	struct slip_init *init = data;
 
-	private = dev->priv;
+	private = netdev_priv(dev);
 	spri = (struct slip_data *) private->user;
 
 	memset(spri->name, 0, sizeof(spri->name));