ALSA: hda/realtek - Add shutup hint

The pin shutup callback seems working well on some devices while it
does harm on some other devices; e.g. Lenovo laptops show often the
noises at (runtime) PM with the pin shutup enabled.

Currently, the only way to disable the pin shutup is to hard-code
  spec->shutup = alc_no_shutup;
in the fixup, and this makes the debugging harder for normal users.
For allowing users to test the similar effect without recompiling the
kernel, this patch adds a new hint string "shutup".  It's a boolean
value, and by passing false to this, user can turn off the pin shutup
call.

For example, to turn off the shutup on Lenovo P50, create a "firmware
patch" file (e.g. /lib/firmware/alsa/lenovo-p50) containing the
following lines:

  [codec]
  0x10ec0298 0x17aa222e 0

  [hint]
  shutup = no

and pass the file via patch option of snd-hda-intel module
(e.g. patch=alsa/lenovo-p50).

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_realtek.c

@@ -793,6 +793,9 @@ static inline void alc_shutup(struct hda_codec *codec)
 {
 	struct alc_spec *spec = codec->spec;
 
+	if (!snd_hda_get_bool_hint(codec, "shutup"))
+		return; /* disabled explicitly by hints */
+
 	if (spec && spec->shutup)
 		spec->shutup(codec);
 	else