fcu_get_rpm
static int fcu_get_rpm(void *, int);
sc->sc_zones[FCU_ZONE_CPU].get_rpm = fcu_get_rpm;
sc->sc_zones[FCU_ZONE_CASE].get_rpm = fcu_get_rpm;
sc->sc_zones[FCU_ZONE_DRIVEBAY].get_rpm = fcu_get_rpm;
current_speed = fcu_get_rpm(sc, which);