ASoC: adau1761: Add ALC controls

The adau1761 has a automatic level control block that can adjust the gain
for the differential input PGA. This patch adds ALSA controls for enabling
and changing the parameter settings for the ALC.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926115012.24049-2-alexandru.ardelean@analog.com


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