ARM: dts: exynos: Remove unneeded address/size cells from fixed-clock on Exynos3250

xusbxti fixed-clock should not have address/size cells because it does
not have any children.  This also fixes DTC W=1 warning:

    arch/arm/boot/dts/exynos3250.dtsi:112.21-139.5:
        Warning (simple_bus_reg): /soc/fixed-rate-clocks: missing or empty reg/ranges property
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos3250.dtsi

@@ -115,8 +115,6 @@ fixed-rate-clocks {
 
 			xusbxti: clock@0 {
 				compatible = "fixed-clock";
-				#address-cells = <1>;
-				#size-cells = <0>;
 				reg = <0>;
 				clock-frequency = <0>;
 				#clock-cells = <0>;