The OLPC has a privacy light hooked up in series with the microphone's
V_Ref bias.  We want to activate the bias while we are capturing audio.
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Andres Salomon <dilinger@debian.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>