net: fec: fix ethtool set_pauseparam duplex bug

Setting the pause parameters causes a running network interface to be
restarted.  However, the restart forces the FEC into half-duplex mode,
whether or not the remote end is in half-duplex mode.  Misconfigured
duplex mode is a known source of problems on a link.

Fix this by always preserving the duplex mode on configuration changes.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -1897,7 +1897,7 @@ static int fec_enet_set_pauseparam(struct net_device *ndev,
 		phy_start_aneg(fep->phy_dev);
 	}
 	if (netif_running(ndev))
-		fec_restart(ndev, 0);
+		fec_restart(ndev, fep->full_duplex);
 
 	return 0;
 }