dt-bindings: iio: dac: Add adi,ad3530r.yaml

dt-bindings: iio: dac: Add adi,ad3530r.yaml

Document the AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel)
low-power, 16-bit, buffered voltage output DACs with software-
programmable gain controls. They provide full-scale output spans of 2.5V
or 5V for reference voltages of 2.5V. These devices operate on a single
2.7V to 5.5V supply and are guaranteed to be monotonic by design.
The "R" variants include a 2.5V, 5ppm/°C internal reference, which is
disabled by default.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
Link: https://patch.msgid.link/20250429-togreg-v7-2-0af9c543b545@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>