net/fsl: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/freescale/xgmac_mdio.c b/drivers/net/ethernet/freescale/xgmac_mdio.c
index cd40b68..7b8fe86 100644
--- a/drivers/net/ethernet/freescale/xgmac_mdio.c
+++ b/drivers/net/ethernet/freescale/xgmac_mdio.c
@@ -307,7 +307,7 @@
 	return 0;
 }
 
-static struct of_device_id xgmac_mdio_match[] = {
+static const struct of_device_id xgmac_mdio_match[] = {
 	{
 		.compatible = "fsl,fman-xmdio",
 	},