i40evf: make ethtool_ops const

Const-ify the ethtool_ops structure, as it is extremely unlikely to
change at runtime. Suggested by Ben Hutchings.

CC: Ben Hutchings <ben@decadent.org.uk>
Change-ID: I1ccb1b7c3ea801cc934447599a35910e7c93d321
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c

@@ -680,7 +680,7 @@ static int i40evf_set_rxfh_indir(struct net_device *netdev, const u32 *indir)
 	return 0;
 }
 
-static struct ethtool_ops i40evf_ethtool_ops = {
+static const struct ethtool_ops i40evf_ethtool_ops = {
 	.get_settings		= i40evf_get_settings,
 	.get_drvinfo		= i40evf_get_drvinfo,
 	.get_link		= ethtool_op_get_link,