net: fec: restore dev_id in the cases of probe error

The static variable dev_id always plus one before netdev registerred.
It should restore the dev_id value in the cases of probe error.
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -3556,6 +3556,7 @@ fec_probe(struct platform_device *pdev)
 	of_node_put(phy_node);
 failed_ioremap:
 	free_netdev(ndev);
+	dev_id--;
 
 	return ret;
 }