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

This reverts commit c57911eb.

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

drivers/scsi/virtio_scsi.c

@@ -977,7 +977,6 @@ static unsigned int features[] = {
 static struct virtio_driver virtio_scsi_driver = {
 	.feature_table = features,
 	.feature_table_size = ARRAY_SIZE(features),
-	.suppress_used_validation = true,
 	.driver.name = KBUILD_MODNAME,
 	.driver.owner = THIS_MODULE,
 	.id_table = id_table,