arm: dts: mt7623: add clock-frequency to CPU nodes

Add clock-frequency property to CPU nodes. Avoids warnings like
[    0.001568] /cpus/cpu@0 missing clock-frequency property
[    0.001588] /cpus/cpu@1 missing clock-frequency property
[    0.001601] /cpus/cpu@2 missing clock-frequency property
[    0.001614] /cpus/cpu@3 missing clock-frequency property
at boot time
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm/boot/dts/mt7623.dtsi

@@ -89,24 +89,28 @@ cpu0: cpu@0 {
 			#cooling-cells = <2>;
 			cooling-min-level = <0>;
 			cooling-max-level = <7>;
+			clock-frequency = <1300000000>;
 		};
 		cpu1: cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a7";
 			reg = <0x1>;
 			operating-points-v2 = <&cpu_opp_table>;
+			clock-frequency = <1300000000>;
 		};
 		cpu2: cpu@2 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a7";
 			reg = <0x2>;
 			operating-points-v2 = <&cpu_opp_table>;
+			clock-frequency = <1300000000>;
 		};
 		cpu3: cpu@3 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a7";
 			reg = <0x3>;
 			operating-points-v2 = <&cpu_opp_table>;
+			clock-frequency = <1300000000>;
 		};
 	};