ASoC: es7134: add es7134 DAC driver

The es7134 is 24bit, 192Khz i2s DA converter for PCM audio.
Datasheet is available here : http://www.everest-semi.com/pdf/ES7134LV%20DS.pdf



This driver is also compatible with the es7144, which is the same as the
es7134, with 2 additional pins for filtering capacitors.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Mark Brown <broonie@kernel.org>