[forcedeth] Clear the MII link status register on link status changes

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/forcedeth.c

 forcedeth_link_status ( struct net_device *netdev )
 {
 	struct forcedeth_private *priv = netdev_priv ( netdev );
+	void *ioaddr = priv->mmio_addr;
+	u32 mii_status;
+
+	/* Clear the MII link change status */
+	mii_status = readl ( ioaddr + NvRegMIIStatus );
+	writel ( NVREG_MIISTAT_LINKCHANGE, ioaddr + NvRegMIIStatus );
 
 	if ( nv_update_linkspeed ( priv ) == 1 )
 		netdev_link_up ( netdev );