ASoC: wcd9320: Add sound control bits

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ASoC: sound_control: Initialize cache reg values

* AOSP framework may initialize with garbage value
  and same gets stored in cache reg.
* This will help to avoid such circumstances.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>