virtio: cull virtio_bus_set_vdev_features

virtio: cull virtio_bus_set_vdev_features

The only user of this function was virtio-ccw, and it should use
virtio_set_features() like everybody else: We need to make sure
that bad features are masked out properly, which this function did
not do.

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