ARM: dts: imx6qdl-sabresd: Use IMX6QDL_CLK_CKO define

Use IMX6QDL_CLK_CKO definition instead of its hard coded clock number for better
readability.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6qdl-sabresd.dtsi

@@ -179,7 +179,7 @@ &i2c1 {
 	codec: wm8962@1a {
 		compatible = "wlf,wm8962";
 		reg = <0x1a>;
-		clocks = <&clks 201>;
+		clocks = <&clks IMX6QDL_CLK_CKO>;
 		DCVDD-supply = <&reg_audio>;
 		DBVDD-supply = <&reg_audio>;
 		AVDD-supply = <&reg_audio>;