net: make ethtool_ops const

Auditing all usage of ethtool_ops found several drivers that
are not declaring the struct const when it should be.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/freescale/fec.c b/drivers/net/ethernet/freescale/fec.c
index b0b0445..20c2e3f 100644
--- a/drivers/net/ethernet/freescale/fec.c
+++ b/drivers/net/ethernet/freescale/fec.c
@@ -1152,7 +1152,7 @@
 	strcpy(info->bus_info, dev_name(&ndev->dev));
 }
 
-static struct ethtool_ops fec_enet_ethtool_ops = {
+static const struct ethtool_ops fec_enet_ethtool_ops = {
 	.get_settings		= fec_enet_get_settings,
 	.set_settings		= fec_enet_set_settings,
 	.get_drvinfo		= fec_enet_get_drvinfo,