ALSA: hda/realtek - Add a model for Thinkpad T570 without DAC workaround

ALSA: hda/realtek - Add a model for Thinkpad T570 without DAC workaround

We fixed the regression of the speaker volume for some Thinkpad models
(e.g. T570) by the commit d92f66f7f977 ("ALSA: hda/realtek - Fix
speaker output regression on Thinkpad T570").  Essentially it fixes
the DAC / pin pairing by a static table.  It was confirmed and merged
to stable kernel later.

Now, interestingly, we got another regression report for the very same
model (T570) about the similar problem, and the commit above was the
culprit.  That is, by some reason, there are devices that prefer the
DAC1, and another device DAC2!

Unfortunately those have the same ID and we have no idea what can
differentiate, in this patch, a new fixup model "tpt470-dock-fix" is
provided, so that users with such a machine can apply it manually.
When model=tpt470-dock-fix option is passed to snd-hda-intel module,
it avoids the fixed DAC pairing and the DAC1 is assigned to the
speaker like the earlier versions.

Fixes: d92f66f7f977 ("ALSA: hda/realtek - Fix speaker output regression on Thinkpad T570")
BugLink: https://apibugzilla.suse.com/show_bug.cgi?id=1172017
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200526062406.9799-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>