dt-bindings: iio: adc: Add rockchip,rk3588-saradc string

Add rockchip,rk3588-saradc compatible string.
Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230603185340.13838-9-shreeya.patel@collabora.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/rockchip-saradc.yaml

@@ -21,6 +21,7 @@ properties:
               - rockchip,rk3308-saradc
               - rockchip,rk3328-saradc
               - rockchip,rk3568-saradc
+              - rockchip,rk3588-saradc
               - rockchip,rv1108-saradc
               - rockchip,rv1126-saradc
           - const: rockchip,rk3399-saradc