ALSA: hda: Fix 0 dB for Lenovo models using Conexant CX20549 (Venice)

ALSA: hda: Fix 0 dB for Lenovo models using Conexant CX20549 (Venice)

Reference: http://mailman.alsa-project.org/pipermail/alsa-devel/2010-May/027525.html

As reported on the mailing list, we also need to cap to the 0 dB offset
for Lenovo models, else the sound will be distorted.

Reported-and-Tested-by: Tim Starling <tstarling@wikimedia.org>
Cc: <stable@kernel.org>
Signed-off-by: Daniel T Chen <crimsun@ubuntu.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>