* Digi MCA ADCs of ConnectCore 6UL device tree bindings

The MCA ADC driver allows to read voltages from the MCA IOs that are ADC
capable. Check the MCA ADC-capable IOs on the CC6UL Hardware Reference Manual.

Also, the ADC inputs can be configured as analog comparators. In this mode the
input is sampled periodically and an interrupt is generated based on the
comparison of the value with two thresholds. See the documentation for more
information on this feature.

Required properties:
- compatible: must be "digi,mca-cc6ul-adc".

Optional properties:
- digi,adc-ch-list: list of MCA IOs to be enabled as ADCs
- digi,comparator-ch-list: list of MCA IOs to be enabled as Analog Comparators
- digi,adc-vref: ADC reference voltage in uV, corresponds with the VCC_MCA
  voltage.
- digi,internal-vref: if present, the internal 1.2 V reference will be used.
  This will force MCA_IO2/EXT_VREF to be configured as a 1.2 V output, and a
  100 nF capacitor must be placed between this line and GND for it to work
  properly.
  If this property is set, the value in 'digi,adc-vref' will be ignored.

Example:

	&mca_adc {
		digi,adc-ch-list = <0 4>;
		digi,comparator-ch-list = <3>;
		digi,adc-vref = <3000000>;
	};
