dt-bindings: iio: adc: add ADI ad4030, ad4630 and ad4632

dt-bindings: iio: adc: add ADI ad4030, ad4630 and ad4632

This adds a binding specification for the Analog Devices Inc. AD4030,
AD4630 and AD4632 families of ADCs.

- ad4030-24 is a 1 channel SAR ADC with 24 bits of precision and a
  sampling rate of 2M samples per second
- ad4032-24 is a 1 channel SAR ADC with 24 bits of precision and a
  sampling rate of 500K samples per second
- ad4630-16 is a 2 channels SAR ADC with 16 bits of precision and a
  sampling rate of 2M samples per second
- ad4630-24 is a 2 channels SAR ADC with 24 bits of precision and a
  sampling rate of 2M samples per second
- ad4632-16 is a 2 channels SAR ADC with 16 bits of precision and a
  sampling rate of 500K samples per second
- ad4632-24 is a 2 channels SAR ADC with 24 bits of precision and a
  sampling rate of 500K samples per second

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Esteban Blanc <eblanc@baylibre.com>
Link: https://patch.msgid.link/20250214-eblanc-ad4630_v1-v4-1-135dd66cab6a@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>