[ALSA] hda-intel - Add black/whitelist for position_fix option

Some devices are known to require position_fix=1 or 2 to make the
driver working correctly.  Otherwise the sound gets weird effects,
such as stutters.
Now a black/whitelist is introduced to indicate the position_fix
value explicitly for such misbehaving hardwares.  As a first example,
Dell D820 is listed there.  More will come later likely...

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>