Add support for reading analog values via the standard Linux IIO
interface. This can be used on Replicape boards to sample analog
input pins.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Return the number of clock ticks to wait directly from
gpio_adc_sample(). This simplifies the ADC interface.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>