drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/fs_enet/fs_enet-main.c b/drivers/net/fs_enet/fs_enet-main.c
index df62506..34412bc 100644
--- a/drivers/net/fs_enet/fs_enet-main.c
+++ b/drivers/net/fs_enet/fs_enet-main.c
@@ -908,7 +908,7 @@
 	fep->msg_enable = value;
 }
 
-static struct ethtool_ops fs_ethtool_ops = {
+static const struct ethtool_ops fs_ethtool_ops = {
 	.get_drvinfo = fs_get_drvinfo,
 	.get_regs_len = fs_get_regs_len,
 	.get_settings = fs_get_settings,