Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

# gpg: Signature made Tue 28 Jun 2016 14:23:24 BST
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  virtio-blk: add num-queues device property
  virtio-blk: dataplane multiqueue support
  virtio-blk: live migrate s->rq with multiqueue
  virtio-blk: associate request with a virtqueue
  virtio-blk: tell dataplane which vq to notify
  virtio-blk: multiqueue batch notify
  virtio-blk: add VirtIOBlockConf->num_queues
  dma-helpers: dma_blk_io() cancel support
  Revert "virtio: sync the dataplane vring state to the virtqueue before virtio_save"

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>