ALSA: hda/hdmi - Work around "alsactl restore" errors

When "alsactl restore" is performed on HDMI codecs, it tries to
restore the channel map value since the channel map controls are
writable.  But hdmi_chmap_ctl_put() returns -EBADFD when no PCM stream
is assigned yet, and this results in an error message from alsactl.
Although the error is harmless, it's certainly ugly and can be
regarded as a regression.

As a workaround, this patch changes the return code in such a case to
be zero for making others happy.  (A slight excuse is: when the chmap
is changed through the proper alsa-lib API, the PCM status is checked
there anyway, so we don't have to be too strict in the kernel side.)

Cc: <stable@vger.kernel.org> [v3.7+]
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_hdmi.c

@@ -1502,7 +1502,7 @@ static int hdmi_chmap_ctl_put(struct snd_kcontrol *kcontrol,
 	ctl_idx = snd_ctl_get_ioffidx(kcontrol, &ucontrol->id);
 	substream = snd_pcm_chmap_substream(info, ctl_idx);
 	if (!substream || !substream->runtime)
-		return -EBADFD;
+		return 0; /* just for avoiding error from alsactl restore */
 	switch (substream->runtime->status->state) {
 	case SNDRV_PCM_STATE_OPEN:
 	case SNDRV_PCM_STATE_SETUP: