In MediaTek SoC chip we have multiple DAI,
such as I2S, ADDA, PCM, etc.

Organize each DAI in to one sub dai,
with its dai driver, controls, widgets, routes.

add mtk_afe_combine_sub_dai() to combine
dai driver from each DAI.

add mtk_afe_add_sub_dai_control() to register
the control, widget, routes to component.
Signed-off-by: KaiChieh Chuang <kaichieh.chuang@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>