Revert "virtio-net: don't let virtio core to validate used length"

This reverts commit 816625c1.

Attempts to validate length in the core did not work out.
We'll drop them, so revert the dependent changes in drivers.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/net/virtio_net.c

@@ -3423,7 +3423,6 @@ static struct virtio_driver virtio_net_driver = {
 	.feature_table_size = ARRAY_SIZE(features),
 	.feature_table_legacy = features_legacy,
 	.feature_table_size_legacy = ARRAY_SIZE(features_legacy),
-	.suppress_used_validation = true,
 	.driver.name =	KBUILD_MODNAME,
 	.driver.owner =	THIS_MODULE,
 	.id_table =	id_table,