wskbd_set_mixervolume_dev
wskbd_set_mixervolume_dev(sc->sc_audiocookie, 0, 1);
wskbd_set_mixervolume_dev(sc->sc_audiocookie, -1, 1);
wskbd_set_mixervolume_dev(sc->sc_audiocookie, 1, 1);
extern int wskbd_set_mixervolume_dev(void *, long, long);