dt-bindings: iio: dac: ad5791: Add optional reset, clr and ldac gpios

Depending on board layout, the ad57xx may need control of reset, clear,
and ldac pins by the host driver. Add optional bindings for these gpios.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Link: https://patch.msgid.link/20241031071746.848694-2-ahaslam@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/dac/adi,ad5791.yaml

@@ -31,6 +31,17 @@ properties:
       gain of two configuration.
     type: boolean
 
+  reset-gpios:
+    maxItems: 1
+
+  clear-gpios:
+    maxItems: 1
+
+  ldac-gpios:
+    description:
+      LDAC pin to be used as a hardware trigger to update the DAC channels.
+    maxItems: 1
+
 required:
   - compatible
   - reg
@@ -44,6 +55,7 @@ unevaluatedProperties: false
 
 examples:
   - |
+    #include <dt-bindings/gpio/gpio.h>
     spi {
         #address-cells = <1>;
         #size-cells = <0>;
@@ -53,6 +65,9 @@ examples:
             reg = <0>;
             vss-supply = <&dac_vss>;
             vdd-supply = <&dac_vdd>;
+            reset-gpios = <&gpio_bd 16 GPIO_ACTIVE_LOW>;
+            clear-gpios = <&gpio_bd 17 GPIO_ACTIVE_LOW>;
+            ldac-gpios = <&gpio_bd 18 GPIO_ACTIVE_HIGH>;
         };
     };
 ...