Reference: Ubuntu #84973 (https://launchpad.net/bugs/84973)
Reference: Linux #8001 (http://bugzilla.kernel.org/show_bug.cgi?id=8001)

Make the mute LED function properly on this unknown HP model.
Signed-off-by: Daniel T Chen <seven.steps@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>