drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/arm/at91_ether.c b/drivers/net/arm/at91_ether.c
index 85493b7..95b28aa 100644
--- a/drivers/net/arm/at91_ether.c
+++ b/drivers/net/arm/at91_ether.c
@@ -648,7 +648,7 @@
 	strlcpy(info->bus_info, dev->class_dev.dev->bus_id, sizeof(info->bus_info));
 }
 
-static struct ethtool_ops at91ether_ethtool_ops = {
+static const struct ethtool_ops at91ether_ethtool_ops = {
 	.get_settings	= at91ether_get_settings,
 	.set_settings	= at91ether_set_settings,
 	.get_drvinfo	= at91ether_get_drvinfo,