ALSA: hda - Add a quirk model for fixing Huawei Matebook X right speaker

[ This is rather a revival of the patch Tomas sent in months ago, but
  applying only with the quirk model option -- tiwai ]

Hard coded coefficients to make Huawuei Matebook X right speaker
work. The Matebook X has a ALC298, please refer to bug 197801 on
how these numbers were reverse engineered from the Windows driver

The reversed engineered sequence represents a repeating pattern
of verbs, and the only values that are changing periodically are
written on indexes 0x23 and 0x25:

0x500, 0x23
0x400, VALUE1
0x500, 0x25
0x400, VALUE2

* skipped reading sequences (0x500 - 0xc00 sequences are ignored)
* static values from reverse engineering are used

NOTE: since a significant risk is still considered, this is provided
as an experimental fix that isn't applied as default for now.  For
enabling the fix, you'll have to choose huawei-mbx-stereo via model
option of snd-hda-intel module.

If we get feedback from users that this works stably, we may apply it
per default.

[ Some coding style fixes and replacement with AC_VERB_* by tiwai ]

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=197801
Signed-off-by: Tomas Espeleta <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>

Documentation/sound/hd-audio/models.rst

@@ -260,6 +260,9 @@ alc295-hp-x360
     HP Spectre X360 fixups
 alc-sense-combo
     Headset button support for Chrome platform
+huawei-mbx-stereo
+    Enable initialization verbs for Huawei MBX stereo speakers;
+    might be risky, try this at your own risk
 
 ALC66x/67x/892
 ==============