ASoC: Intel: sof-rt5682: add mclk_en to sof_rt5682_private

Add a variable mclk_en to sof_rt5682_private structure to reduce
global variable access. No functional change.

Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Brent Lu <brent.lu@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20240426152529.38345-18-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>