drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/sungem.c b/drivers/net/sungem.c
index eb8a476..e567d0a 100644
--- a/drivers/net/sungem.c
+++ b/drivers/net/sungem.c
@@ -2753,7 +2753,7 @@
 	return 0;
 }
 
-static struct ethtool_ops gem_ethtool_ops = {
+static const struct ethtool_ops gem_ethtool_ops = {
 	.get_drvinfo		= gem_get_drvinfo,
 	.get_link		= ethtool_op_get_link,
 	.get_settings		= gem_get_settings,