wireguard: switch to dev_get_tstats64

Replace ip_tunnel_get_stats64() with the new identical core function
dev_get_tstats64().
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/wireguard/device.c

@@ -215,7 +215,7 @@ static const struct net_device_ops netdev_ops = {
 	.ndo_open		= wg_open,
 	.ndo_stop		= wg_stop,
 	.ndo_start_xmit		= wg_xmit,
-	.ndo_get_stats64	= ip_tunnel_get_stats64
+	.ndo_get_stats64	= dev_get_tstats64
 };
 
 static void wg_destruct(struct net_device *dev)