Adds a driver for Asahi Kasei's AK5386 Single-ended 24-Bit 192kHz
delta-sigma ADC. The device has no control port interface but an
optional RESET/PDN GPIO pin.
Signed-off-by: NDaniel Mack <zonque@gmail.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>