ALSA: hda - add mute LED for HP Pavilion 17 (Realtek codec)

ALSA: hda - add mute LED for HP Pavilion 17 (Realtek codec)

commit 6d3cd5d444223c41eabb70dccff14fae4e8cb8b1 upstream.

The mute LED is in this case connected to the Mic1 VREF.

The machine also exposes the following string in BIOS:
"HP_Mute_LED_0_A", so if more machines are coming, it probably
makes sense to try to do something more generic, like for the
IDT codec.

BugLink: https://bugs.launchpad.net/bugs/1096789
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>