Add support for Allo Piano DAC 2.1 plus add-on board for Raspberry Pi.

The Piano DAC 2.1 has support for 4 channels with subwoofer.

Signed-off-by: Baswaraj K <jaikumar@cem-solutions.net>
Reviewed-by: Vijay Kumar B. <vijaykumar@zilogic.com>
Reviewed-by: Raashid Muhammed <raashidmuhammed@zilogic.com>

Add clock changes and mute gpios (#1938)

Also improve code style and adhere to ALSA coding conventions.

Signed-off-by: Baswaraj K <jaikumar@cem-solutions.net>
Reviewed-by: Vijay Kumar B. <vijaykumar@zilogic.com>
Reviewed-by: Raashid Muhammed <raashidmuhammed@zilogic.com>

PianoPlus: Dual Mono & Dual Stereo features added (#2069)

allo-piano-dac-plus: Master volume added + fixes

Master volume added, which controls both DACs volumes.

See: https://github.com/raspberrypi/linux/pull/2149



Also fix initial max volume, default mode value, and unmute.

Signed-off-by: allocom <sparky-dev@allo.com>