STA333BW power-amplifier I²C control support

[renne]

The ST STA333BW is a 2x20W I²S power-amplifier IC around 3.50 €. Besides power-supply and 4 inductors it only needs 1 electrolytic capacitor, 2 THT capacitors, 22 SMD capacitors and 9 SMD resistors for a stereo configuration.

It provides the followiing 3 power output configurations:
– 2 channels of ternary PWM (2 x 20 W into 8 Ω at 18 V) + PWM output
– 2 channels of ternary PWM (2 x 20 W into 8 Ω at 18 V) + ternary stereo line-out
– 2.1 channels of binary PWM (left, right, LFE) (2 x 9 W into 4 Ω +1 x 20 W into 8 Ω at 18 V)

This issue is meant as a starting point to implement ESP-ADF-support for more powerful power-amplifiers than on the LyraT boards.