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/fs_enet/fs_enet-main.c b/drivers/net/fs_enet/fs_enet-main.c
index 940e204..67b4b07 100644
--- a/drivers/net/fs_enet/fs_enet-main.c
+++ b/drivers/net/fs_enet/fs_enet-main.c
@@ -1178,7 +1178,7 @@
 
 	data  = of_get_property(np, "fixed-link", NULL);
 	if (data) {
-		snprintf(fpi->bus_id, 16, PHY_ID_FMT, 0, *data);
+		snprintf(fpi->bus_id, 16, "%x:%02x", 0, *data);
 		return 0;
 	}
 
@@ -1202,7 +1202,7 @@
 	if (!data || len != 4)
 		goto out_put_mdio;
 
-	snprintf(fpi->bus_id, 16, PHY_ID_FMT, res.start, *data);
+	snprintf(fpi->bus_id, 16, "%x:%02x", res.start, *data);
 
 out_put_mdio:
 	of_node_put(mdionode);