drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/e1000/e1000_ethtool.c b/drivers/net/e1000/e1000_ethtool.c
index 3fccffd..0759bf0 100644
--- a/drivers/net/e1000/e1000_ethtool.c
+++ b/drivers/net/e1000/e1000_ethtool.c
@@ -1922,7 +1922,7 @@
 	}
 }
 
-static struct ethtool_ops e1000_ethtool_ops = {
+static const struct ethtool_ops e1000_ethtool_ops = {
 	.get_settings           = e1000_get_settings,
 	.set_settings           = e1000_set_settings,
 	.get_drvinfo            = e1000_get_drvinfo,