ARM: dts: imx6q-prti6q: Fix ref/tcxo-clock-frequency properties

make dtbs_check gives the following errors:

ref-clock-frequency: size (9) error for type uint32
tcxo-clock-frequency: size (9) error for type uint32

Fix it by passing the frequencies inside < > as documented in
Documentation/devicetree/bindings/net/wireless/ti,wlcore.yaml.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Fixes: 0d446a50 ("ARM: dts: add Protonic PRTI6Q board")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6q-prti6q.dts

@@ -364,8 +364,8 @@ wifi {
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_wifi>;
 		interrupts-extended = <&gpio1 30 IRQ_TYPE_LEVEL_HIGH>;
-		ref-clock-frequency = "38400000";
-		tcxo-clock-frequency = "19200000";
+		ref-clock-frequency = <38400000>;
+		tcxo-clock-frequency = <19200000>;
 	};
 };