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 <[email protected]>
    To: [email protected], [email protected]
    Cc: [email protected], [email protected], [email protected],
    Cornelia Huck <[email protected]>
    Subject: [PATCH RFC v6 00/20] qemu: towards virtio-1 host support
    Message-Id: <1418304322[email protected]>

which is itself still missing some core bits.

Signed-off-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>