ARM: dts: rockchip: remove clock-frequency from saradc node rv1108

An experimental test with the command below gives these errors:

arch/arm/boot/dts/rv1108-elgin-r1.dt.yaml: adc@1038c000:
'clock-frequency'
does not match any of the regexes: 'pinctrl-[0-9]+'
arch/arm/boot/dts/rv1108-evb.dt.yaml: adc@1038c000:
'clock-frequency'
does not match any of the regexes: 'pinctrl-[0-9]+'

'clock-frequency' is not a valid property for a saradc node,
so remove it.

make ARCH=arm dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/iio/adc/
rockchip-saradc.yaml
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20200313132646.10317-1-jbx6244@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rv1108.dtsi

@@ -366,7 +366,6 @@ adc: adc@1038c000 {
 		reg = <0x1038c000 0x100>;
 		interrupts = <GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>;
 		#io-channel-cells = <1>;
-		clock-frequency = <1000000>;
 		clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
 		clock-names = "saradc", "apb_pclk";
 		status = "disabled";