virtio-pci: initial virtio 1.0 support

virtio-pci: initial virtio 1.0 support

This is somewhat functional.  With this, and linux driver from my tree,
I was able to use virtio net as virtio 1.0 device for light browsing.

At the moment, dataplane and vhost code is
still missing.

Based on Cornelia's virtio 1.0 patchset:
    Date: Thu, 11 Dec 2014 14:25:02 +0100
    From: Cornelia Huck <cornelia.huck@de.ibm.com>
    To: virtualization@lists.linux-foundation.org, qemu-devel@nongnu.org
    Cc: rusty@rustcorp.com.au, thuth@linux.vnet.ibm.com, mst@redhat.com,
    Cornelia Huck <cornelia.huck@de.ibm.com>
    Subject: [PATCH RFC v6 00/20] qemu: towards virtio-1 host support
    Message-Id: <1418304322-7546-1-git-send-email-cornelia.huck@de.ibm.com>

which is itself still missing some core bits.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>