drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/forcedeth.c b/drivers/net/forcedeth.c
index 59f9a51..b8df5ca 100644
--- a/drivers/net/forcedeth.c
+++ b/drivers/net/forcedeth.c
@@ -3962,7 +3962,7 @@
 	}
 }
 
-static struct ethtool_ops ops = {
+static const struct ethtool_ops ops = {
 	.get_drvinfo = nv_get_drvinfo,
 	.get_link = ethtool_op_get_link,
 	.get_wol = nv_get_wol,