ASoC: SOF: Intel: hda-mlink: fix off-by-one error

The HCHAN parameter should be the highest channel number, not the
channel count.

While we're at it, handle LCHAN with the dual __ffs helper.

Fixes: ccc2f0c1 ("ASoC: SOF: Intel: hda-mlink: add helper to program SoundWire PCMSyCM registers")
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Link: https://lore.kernel.org/r/20230807210959.506849-2-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/intel/hda-mlink.c

@@ -781,6 +781,8 @@ int hdac_bus_eml_sdw_map_stream_ch(struct hdac_bus *bus, int sublink, int y,
 {
 	struct hdac_ext2_link *h2link;
 	u16 __iomem *pcmsycm;
+	int hchan;
+	int lchan;
 	u16 val;
 
 	h2link = find_ext2_link(bus, true, AZX_REG_ML_LEPTR_ID_SDW);
@@ -791,9 +793,17 @@ int hdac_bus_eml_sdw_map_stream_ch(struct hdac_bus *bus, int sublink, int y,
 		h2link->instance_offset * sublink +
 		AZX_REG_SDW_SHIM_PCMSyCM(y);
 
+	if (channel_mask) {
+		hchan = __fls(channel_mask);
+		lchan = __ffs(channel_mask);
+	} else {
+		hchan = 0;
+		lchan = 0;
+	}
+
 	mutex_lock(&h2link->eml_lock);
 
-	hdaml_shim_map_stream_ch(pcmsycm, 0, hweight32(channel_mask),
+	hdaml_shim_map_stream_ch(pcmsycm, lchan, hchan,
 				 stream_id, dir);
 
 	mutex_unlock(&h2link->eml_lock);