Revert "virtio_pci: remove struct virtio_pci_vq_info"

This reverts commit 5c34d002

.

Conflicts:
	drivers/virtio/virtio_pci_common.c

The cleanup seems to be one of the changes that broke
hybernation for some users. We are still not sure why
but revert helps.

This reverts the cleanup changes but keeps the affinity support.

Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>