ALSA: hda - introduce HDA_SUBDEV_AMP_FLAG (ControlAmp in proc)

The purpose of this changeset is to show information about amplifier
setting in the codec proc file. Something like:

  Control: name="Front Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Front Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=2, ofs=0

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/pci/hda/patch_cirrus.c

@@ -500,6 +500,7 @@ static int add_mute(struct hda_codec *codec, const char *name, int index,
 	knew.private_value = pval;
 	snprintf(tmp, sizeof(tmp), "%s %s Switch", name, dir_sfx[dir]);
 	*kctlp = snd_ctl_new1(&knew, codec);
+	(*kctlp)->id.subdevice = HDA_SUBDEV_AMP_FLAG;
 	return snd_hda_ctl_add(codec, get_amp_nid_(pval), *kctlp);
 }
 
@@ -513,6 +514,7 @@ static int add_volume(struct hda_codec *codec, const char *name,
 	knew.private_value = pval;
 	snprintf(tmp, sizeof(tmp), "%s %s Volume", name, dir_sfx[dir]);
 	*kctlp = snd_ctl_new1(&knew, codec);
+	(*kctlp)->id.subdevice = HDA_SUBDEV_AMP_FLAG;
 	return snd_hda_ctl_add(codec, get_amp_nid_(pval), *kctlp);
 }