drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 9429859..c4c51f1 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -3033,7 +3033,7 @@
 		      regs->len - B3_RI_WTO_R1);
 }
 
-static struct ethtool_ops sky2_ethtool_ops = {
+static const struct ethtool_ops sky2_ethtool_ops = {
 	.get_settings = sky2_get_settings,
 	.set_settings = sky2_set_settings,
 	.get_drvinfo = sky2_get_drvinfo,