Add mixer controls and correct headphone detection bits for PowerMacs
7300/7500 (AWACS) and G3 Beige (Screamer), and iMac G3 Slot-loading
(Screamer).
Signed-off-by: NRisto Suominen <Risto.Suominen@gmail.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>