virtio-queue: Update crate based on latest rust-vmm/vm-virtio

This crate contains up to date definition of the Queue, AvailIter,
DescriptorChain and Descriptor structures forked from the upstream
crate rust-vmm/vm-virtio 27b18af01ee2d9564626e084a758a2b496d2c618.

The following patches have been applied on top of this base in order to
make it work correctly with Cloud Hypervisor requirements:

- Add MSI vector field to the Queue

  In order to help with MSI/MSI-X support, it is convenient to store the
  value of the interrupt vector inside the Queue directly.

- Handle address translations

  For devices with access to data in memory being translated, we add to
  the Queue the ability to translate the address stored in the
  descriptor.
  It is very helpful as it performs the translation right after the
  untranslated address is read from memory, avoiding any errors from
  happening from the consumer's crate perspective. It also allows the
  consumer to reduce greatly the amount of duplicated code for applying
  the translation in many different places.

- Add helpers for Queue structure

  They are meant to help crate's consumers getting/setting information
  about the Queue.

These patches can be found on the 'ch' branch from the Cloud Hypervisor
fork: https://github.com/cloud-hypervisor/vm-virtio.git

This patch takes care of updating the Cloud Hypervisor code in
virtio-devices and vm-virtio to build correctly with the latest version
of virtio-queue.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

block_util/src/lib.rs

@@ -36,7 +36,7 @@ use virtio_bindings::bindings::virtio_blk::*;
 use virtio_queue::DescriptorChain;
 use vm_memory::{
     bitmap::AtomicBitmap, bitmap::Bitmap, ByteValued, Bytes, GuestAddress, GuestMemory,
-    GuestMemoryAtomic, GuestMemoryError,
+    GuestMemoryError, GuestMemoryLoadGuard,
 };
 use vmm_sys_util::eventfd::EventFd;
 
@@ -176,7 +176,7 @@ pub struct Request {
 
 impl Request {
     pub fn parse(
-        desc_chain: &mut DescriptorChain<GuestMemoryAtomic<GuestMemoryMmap>>,
+        desc_chain: &mut DescriptorChain<GuestMemoryLoadGuard<GuestMemoryMmap>>,
     ) -> result::Result<Request, Error> {
         let hdr_desc = desc_chain
             .next()