iio: adc: ad7173: Add support for AD411x devices

Add support for AD4111/AD4112/AD4114/AD4115/AD4116.

The AD411X family encompasses a series of low power, low noise, 24-bit,
sigma-delta analog-to-digital converters that offer a versatile range of
specifications.

This family of ADCs integrates an analog front end suitable for processing
both fully differential and single-ended, bipolar voltage inputs
addressing a wide array of industrial and instrumentation requirements.

- All ADCs have inputs with a precision voltage divider with a division
  ratio of 10.
- AD4116 has 5 low level inputs without a voltage divider.
- AD4111 and AD4112 support current inputs (0 mA to 20 mA) using a 50ohm
  shunt resistor.
Signed-off-by: Dumitru Ceclan <dumitru.ceclan@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240607-ad4111-v7-9-97e3855900a0@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>