ethernet: fec: use eth_hw_addr_gen()

Commit 406f42fa ("net-next: When a bond have a massive amount
of VLANs...") introduced a rbtree for faster Ethernet address look
up. To maintain netdev->dev_addr in this tree we need to make all
the writes to it got through appropriate helpers.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -1768,11 +1768,8 @@ static int fec_get_mac(struct net_device *ndev)
 		return 0;
 	}
 
-	eth_hw_addr_set(ndev, iap);
-
 	/* Adjust MAC if using macaddr */
-	if (iap == macaddr)
-		 ndev->dev_addr[ETH_ALEN-1] = macaddr[ETH_ALEN-1] + fep->dev_id;
+	eth_hw_addr_gen(ndev, iap, iap == macaddr ? fep->dev_id : 0);
 
 	return 0;
 }