Apparently some firmware versions forget enabling the dual-edge bit,
snd-powermac did that too and even OSX does sometimes. This should fix
headphone plug detection on those machines.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>