ASoC: codecs: Add aw88081 amplifier driver

Merge series from wangweidong.a@awinic.com:

Add the awinic,aw88081 property to support the aw88081 chip.

The driver is for amplifiers aw88081 of Awinic Technology
Corporation. The awinic AW88081 is an I2S/TDM input,
high efficiency digital Smart K audio amplifier