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/slirp_kern.c b/arch/um/drivers/slirp_kern.c
index d987af2..f15a6e7 100644
--- a/arch/um/drivers/slirp_kern.c
+++ b/arch/um/drivers/slirp_kern.c
@@ -22,7 +22,7 @@
 	struct slirp_init *init = data;
 	int i;
 
-	private = dev->priv;
+	private = netdev_priv(dev);
 	spri = (struct slirp_data *) private->user;
 
 	spri->argw = init->argw;