drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/e100.c b/drivers/net/e100.c
index 47d9708..dc5e38a 100644
--- a/drivers/net/e100.c
+++ b/drivers/net/e100.c
@@ -2477,7 +2477,7 @@
 	}
 }
 
-static struct ethtool_ops e100_ethtool_ops = {
+static const struct ethtool_ops e100_ethtool_ops = {
 	.get_settings		= e100_get_settings,
 	.set_settings		= e100_set_settings,
 	.get_drvinfo		= e100_get_drvinfo,