smsc911x: don't clobber driver_data

smsc911x uses driver_data to store our net_device, don't overwrite this
with the mii_bus.

Reported and fixed by dfoley@telus.net.
Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/smsc911x.c

@@ -822,7 +822,6 @@ static int __devinit smsc911x_mii_init(struct platform_device *pdev,
 		pdata->mii_bus->irq[i] = PHY_POLL;
 
 	pdata->mii_bus->parent = &pdev->dev;
-	dev_set_drvdata(&pdev->dev, &pdata->mii_bus);
 
 	pdata->using_extphy = 0;