net/fec: Don't let ndo_start_xmit return NETDEV_TX_BUSY without link

Don't test for having link and let hardware deal with this situation.

Without this patch I see a machine running an -rt patched Linux being
stuck in sch_direct_xmit when it looses link while there is still a
packet to be sent. In this case the fec_enet_start_xmit routine returned
NETDEV_TX_BUSY which makes the network stack reschedule the packet and
so sch_direct_xmit calls fec_enet_start_xmit again.
I failed to reproduce a complete hang without -rt, but I think the
problem exists there, too.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -294,11 +294,6 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	unsigned short	status;
 	unsigned int index;
 
-	if (!fep->link) {
-		/* Link is down or auto-negotiation is in progress. */
-		return NETDEV_TX_BUSY;
-	}
-
 	/* Fill in a Tx ring entry */
 	bdp = fep->cur_tx;