commit 7976eb49 upstream.

Otherwise, the mute led can't work at all.
Tested-by: Taihsiang Ho <taihsiang.ho@canonical.com>
BugLink: https://bugs.launchpad.net/bugs/1410704Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>