ethernet/arc/arc_emac: add missing platform_set_drvdata() in arc_emac_probe()

Add missing platform_set_drvdata() in arc_emac_probe(), otherwise
calling platform_get_drvdata() in arc_emac_remove() may returns NULL.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
index d818ded..473c377 100644
--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -671,6 +671,7 @@
 	if (!ndev)
 		return -ENOMEM;
 
+	platform_set_drvdata(pdev, ndev);
 	SET_NETDEV_DEV(ndev, &pdev->dev);
 
 	ndev->netdev_ops = &arc_emac_netdev_ops;