ASoC: SOF: mediatek: mt8195 add shutdown callback

Add mt8195 shutdown callback function implementation to ensure that
shutdown flow is called to shutdown dsp core, disable adsp clock, and
power off dsp sram correctly during reboot flow.

Signed-off-by: YC Hung <yc.hung@mediatek.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20220406194048.289787-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>