vringh: reset kiov 'consumed' field in __vringh_iov()

__vringh_iov() overwrites the contents of riov and wiov, in fact it
resets the 'i' and 'used' fields, but also the 'consumed' field should
be reset to avoid an inconsistent state.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-4-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vringh.c

@@ -290,9 +290,9 @@ __vringh_iov(struct vringh *vrh, u16 i,
 		return -EINVAL;
 
 	if (riov)
-		riov->i = riov->used = 0;
+		riov->i = riov->used = riov->consumed = 0;
 	if (wiov)
-		wiov->i = wiov->used = 0;
+		wiov->i = wiov->used = wiov->consumed = 0;
 
 	for (;;) {
 		void *addr;