ARM: dts: set the 24MHz xtal as parent of the UART clock

This has no practical effect but reflects the actual clock
hierarchy of the system.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/boot/dts/integratorap.dts

@@ -39,6 +39,7 @@
 		#clock-cells = <0>;
 		compatible = "fixed-clock";
 		clock-frequency = <14745600>;
+		clocks = <&xtal24mhz>;
 	};
 
 	syscon {