dt-bindings: iio: adc: Add binding for AD7380 ADCs

This adds a binding specification for the Analog Devices Inc. AD7380
family of ADCs.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240528-adding-new-ad738x-driver-v7-1-4cd70a4c12c8@baylibre.com


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