dt-bindings: adc: add AD7173

The AD7173 family offer a complete integrated Sigma-Delta ADC solution
which can be used in high precision, low noise single channel applications
or higher speed multiplexed applications. The Sigma-Delta ADC is intended
primarily for measurement of signals close to DC but also delivers
outstanding performance with input bandwidths out to ~10kHz.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Dumitru Ceclan <mitrutzceclan@gmail.com>
Link: https://lore.kernel.org/r/20240228110622.25114-1-mitrutzceclan@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>