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/mcast_kern.c b/arch/um/drivers/mcast_kern.c
index 8c4378a..ffc6416 100644
--- a/arch/um/drivers/mcast_kern.c
+++ b/arch/um/drivers/mcast_kern.c
@@ -28,7 +28,7 @@
 	struct mcast_data *dpri;
 	struct mcast_init *init = data;
 
-	pri = dev->priv;
+	pri = netdev_priv(dev);
 	dpri = (struct mcast_data *) pri->user;
 	dpri->addr = init->addr;
 	dpri->port = init->port;