ASoC: mediatek: mt7986: add common header

Add header files for register definition and structure.

Signed-off-by: Maso Huang <maso.huang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230817101338.18782-2-maso.huang@mediatek.com


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