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/mii-fec.c b/drivers/net/fs_enet/mii-fec.c
index a89cf15..ba75efc 100644
--- a/drivers/net/fs_enet/mii-fec.c
+++ b/drivers/net/fs_enet/mii-fec.c
@@ -196,7 +196,7 @@
 	if (ret)
 		return ret;
 
-	new_bus->id = res.start;
+	snprintf(new_bus->id, MII_BUS_ID_SIZE, "%x", res.start);
 
 	fec->fecp = ioremap(res.start, res.end - res.start + 1);
 	if (!fec->fecp)
@@ -309,7 +309,7 @@
 	new_bus->read = &fs_enet_fec_mii_read,
 	new_bus->write = &fs_enet_fec_mii_write,
 	new_bus->reset = &fs_enet_fec_mii_reset,
-	new_bus->id = pdev->id;
+	snprintf(new_bus->id, MII_BUS_ID_SIZE, "%x", pdev->id);
 
 	pdata = (struct fs_mii_fec_platform_info *)pdev->dev.platform_data;