net: tsec: Fix NULL access in case init_phy() fails

If the PHY is not recognized don't access phydev (NULL)
and return 0 to signal failure.
Signed-off-by: NClaudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: NJoe Hershberger <joe.hershberger@ni.com>

drivers/net/tsec.c

@@ -597,6 +597,8 @@ static int init_phy(struct eth_device *dev)
 		tsec_configure_serdes(priv);
 
 	phydev = phy_connect(priv->bus, priv->phyaddr, dev, priv->interface);
+	if (!phydev)
+		return 0;
 
 	phydev->supported &= supported;
 	phydev->advertising = phydev->supported;