These HP machines needs GPIO 4 low to enable the headphone amplifier.
In addition, we still need to control LEDs via vref and GPIO.

Cc: stable@vger.kernel.org
BugLink: https://bugs.launchpad.net/bugs/1387128Tested-by: TienFu Chen <tienfu.chen@canonical.com>
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>