ASoC: dt-bindings: mt8183: add ec-codec

Add an optional property "ec-codec".  If specified, mt8183 could use the
"wake on voice" feature offered by EC codec.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20191019143504.3.Iec97a3f137148cdf316056612590b3e0b302f5f3@changeid


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