vdpa: Block vq property changes in DRIVER_OK

The virtio standard doesn't allow for virtqueue address and state
changes when the device is in DRIVER_OK. Return an error in such cases
unless the device is suspended.

The suspended device exception is needed because some devices support
virtqueue changes when the device is suspended.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Suggested-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20231225134210.151540-3-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>