net/fsl: fix a bug in xgmac_mdio

There is a bug in xgmac_wait_until_done() which mdio_stat should be used
instead of mdio_data when checking if busy bit is cleared.
Signed-off-by: NShaohui Xie <Shaohui.Xie@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/xgmac_mdio.c

@@ -79,7 +79,7 @@ static int xgmac_wait_until_done(struct device *dev,
 
 	/* Wait till the MDIO write is complete */
 	timeout = TIMEOUT;
-	while ((ioread32be(&regs->mdio_data) & MDIO_DATA_BSY) && timeout) {
+	while ((ioread32be(&regs->mdio_stat) & MDIO_STAT_BSY) && timeout) {
 		cpu_relax();
 		timeout--;
 	}