iio: adc: ad7191: add AD7191

AD7191 is a pin-programmable, ultra-low noise 24-bit sigma-delta ADC
designed for precision bridge sensor measurements. It features two
differential analog input channels, selectable output rates,
programmable gain, internal temperature sensor and simultaneous
50Hz/60Hz rejection.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Reviewed-by: David <Lechner&lt;dlechner@baylibre.com>
Link: https://patch.msgid.link/20250228141327.262488-3-alisa.roman@analog.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>