drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/sk98lin/skethtool.c b/drivers/net/sk98lin/skethtool.c
index 4265ed9..e5cb5b5 100644
--- a/drivers/net/sk98lin/skethtool.c
+++ b/drivers/net/sk98lin/skethtool.c
@@ -581,7 +581,7 @@
 	return 0;
 }
 
-struct ethtool_ops SkGeEthtoolOps = {
+const struct ethtool_ops SkGeEthtoolOps = {
 	.get_settings		= getSettings,
 	.set_settings		= setSettings,
 	.get_drvinfo		= getDriverInfo,