net: fec: correct phy_name buffer length when init phy_name

Fix the bug that we got wrong phy_name on imx6q sabrelite board.
snprintf used wrong length of phy_name.
phy_name length is MII_BUS_ID_SIZE + 3 rather not MII_BUS_ID_SIZE.
I change it to sizeof(phy_name).

Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec.c

@@ -990,7 +990,7 @@ static int fec_enet_mii_probe(struct net_device *ndev)
 		phy_id = 0;
 	}
 
-	snprintf(phy_name, MII_BUS_ID_SIZE, PHY_ID_FMT, mdio_bus_id, phy_id);
+	snprintf(phy_name, sizeof(phy_name), PHY_ID_FMT, mdio_bus_id, phy_id);
 	phy_dev = phy_connect(ndev, phy_name, &fec_enet_adjust_link, 0,
 			      fep->phy_interface);
 	if (IS_ERR(phy_dev)) {