phy: Change mii_bus id field to a string

Having the id field be an int was making more complex bus topologies
excessively difficult.  For now, just convert it to a string, and
change all instances of "bus->id = val" to
snprintf(id, MII_BUS_ID_LEN, "%x", val).

Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/phy/fixed.c b/drivers/net/phy/fixed.c
index ca9b040..4e07956 100644
--- a/drivers/net/phy/fixed.c
+++ b/drivers/net/phy/fixed.c
@@ -213,7 +213,7 @@
 		goto err_pdev;
 	}
 
-	fmb->mii_bus.id = 0;
+	snprintf(fmb->mii_bus.id, MII_BUS_ID_SIZE, "0");
 	fmb->mii_bus.name = "Fixed MDIO Bus";
 	fmb->mii_bus.dev = &pdev->dev;
 	fmb->mii_bus.read = &fixed_mdio_read;