ALSA: hda/hdmi: fix warning about PCM count when used with SOF

With commit 13046370c4 ("ALSA: hda/hdmi: let new platforms assign the
pcm slot dynamically"), old behaviour to consider the HDA pin number,
when choosing PCM to assign, was dropped.

Build on this change and limit the number of PCMs created to number of
converters (= maximum number of concurrent display/receivers) when
"mst_no_extra_pcms" and "dyn_pcm_no_legacy" quirks are both set.

Fix the check in hdmi_find_pcm_slot() to ensure only spec->pcm_used
entries are considered in the search. Elsewhere in the driver
spec->pcm_used is already checked properly.

Doing this avoids following warning at SOF driver probe for multiple
machine drivers:

[  112.425297] sof_sdw sof_sdw: hda_dsp_hdmi_build_controls: no
PCM in topology for HDMI converter 4
[  112.425298] sof_sdw sof_sdw: hda_dsp_hdmi_build_controls: no
PCM in topology for HDMI converter 5
[  112.425299] sof_sdw sof_sdw: hda_dsp_hdmi_build_controls: no
PCM in topology for HDMI converter 6

Fixes: 13046370c4 ("ALSA: hda/hdmi: let new platforms assign the pcm slot dynamically")
BugLink: https://github.com/thesofproject/linux/issues/2573
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20220414150516.3638283-1-kai.vehmanen@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_hdmi.c

@@ -1395,7 +1395,7 @@ static int hdmi_find_pcm_slot(struct hdmi_spec *spec,
 
  last_try:
 	/* the last try; check the empty slots in pins */
-	for (i = 0; i < spec->num_nids; i++) {
+	for (i = 0; i < spec->pcm_used; i++) {
 		if (!test_bit(i, &spec->pcm_bitmap))
 			return i;
 	}
@@ -2325,7 +2325,9 @@ static int generic_hdmi_build_pcms(struct hda_codec *codec)
 	 * dev_num is the device entry number in a pin
 	 */
 
-	if (codec->mst_no_extra_pcms)
+	if (spec->dyn_pcm_no_legacy && codec->mst_no_extra_pcms)
+		pcm_num = spec->num_cvts;
+	else if (codec->mst_no_extra_pcms)
 		pcm_num = spec->num_nids;
 	else
 		pcm_num = spec->num_nids + spec->dev_num - 1;