sound: Add an ACPI driver for Maxim MAX98357ac

This chip is used on coral and we need to generate ACPI tables for sound
to make it work. Add a driver that does just this (i.e. at present does
not actually support playing sound).

Signed-off-by: Simon Glass <sjg@chromium.org>
[bmeng: Use the correct acpi_irq_polarity enum number]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>