chelsio: use const for virtual functions

There are several uses of _ops structure in this driver that
can be converted to const.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/chelsio/subr.c b/drivers/net/chelsio/subr.c
index 56d1d15..7de9a61 100644
--- a/drivers/net/chelsio/subr.c
+++ b/drivers/net/chelsio/subr.c
@@ -321,7 +321,7 @@
 }
 
 #if defined(CONFIG_CHELSIO_T1_1G) || defined(CONFIG_CHELSIO_T1_COUGAR)
-static struct mdio_ops mi1_mdio_ops = {
+static const struct mdio_ops mi1_mdio_ops = {
 	.init = mi1_mdio_init,
 	.read = mi1_mdio_read,
 	.write = mi1_mdio_write
@@ -377,7 +377,7 @@
 	return 0;
 }
 
-static struct mdio_ops mi1_mdio_ext_ops = {
+static const struct mdio_ops mi1_mdio_ext_ops = {
 	.init = mi1_mdio_init,
 	.read = mi1_mdio_ext_read,
 	.write = mi1_mdio_ext_write