dt-bindings: iio: potentiometer: Add Maxim DS3502 in trivial-devices

Maxim DS3502 is a 7 bit nonvolatile digital potentiometer.
Add DS3502 binding into trivial-devices.yaml.
Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220223163525.13399-8-jagathjog1996@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -157,6 +157,8 @@ properties:
           - maxim,ds1803-050
             # 100 kOhm digital potentiometer with I2C interface
           - maxim,ds1803-100
+            # 10 kOhm digital potentiometer with I2C interface
+          - maxim,ds3502
             # Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
           - maxim,max1237
             # Temperature Sensor, I2C interface