N20: Fix UART baud rate clock

Author: user890104

arch/arm/boot/dts/samsung/s5l8723-n20.dts

@@ -28,7 +28,7 @@
     nclk: external_clock {
         compatible = "fixed-clock";
         #clock-cells = <0>;
-        clock-frequency = <140000000>;
+        clock-frequency = <24000000>;
         clock-output-names = "nclk";
     };