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

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: ccc2f0c1b6b6 ("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.com
Signed-off-by: Mark Brown <broonie@kernel.org>