BugLink: https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4792

Cristian reported that these models have really bad sound above 6 dB
and proposed the original patch. I've updated the comment to reflect
this change.
Signed-off-by: NDaniel T Chen <crimsun@ubuntu.com>
Reported-by: Cristian Klein
Signed-off-by: NTakashi Iwai <tiwai@suse.de>