ASoC: SOF: mediatek: Provide debugfs_add_region_item ops for core

Set the generic iomem callback for debugfs_add_region_item to support
sof-logger.

Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230110084312.12953-4-tinghan.shen@mediatek.com


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