ASoC: cros_ec_codec: refactor I2S RX

Refactor by the following items:
- reformat copyright declaration
- use more specific name "i2s rx"
- use verbose symbol names to separate namespaces
- make some short functions inline
- remove unused TDM-related code

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Acked-By: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20191014180059.02.I43373b9a66dbb70196b3f216b3aa86111c410836@changeid


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