Add documentation for AD7191 driver.
Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Reviewed-by: David Lechner<dlechner@baylibre.com>
Link: https://patch.msgid.link/20250228141327.262488-4-alisa.roman@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
