ASoC: Add MediaTek MT6660 Speaker Amp Driver

The MT6660 is a boosted BTL class-D amplifier with V/I sensing.
A built-in DC-DC step-up converter is used to provide efficient
power for class-D amplifier with multi-level class-G operation.
The digital audio interface supports I2S, left-justified,
right-justified, TDM and DSP A/B format for audio in with a data
out used for chip information like voltage sense and current
sense, which are able to be monitored via DATAO through proper

Signed-off-by: Jeff Chang <jeff_chang@richtek.com>
Link: https://lore.kernel.org/r/1579153597-23286-1-git-send-email-richtek.jeff.chang@gmail.com


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