ARM: dts: imx6: Do not hardcode the CLKO clock

Using "IMX6QDL_CLK_CKO" for the clock is easier to read instead of
the hardcoded clock number.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
diff --git a/arch/arm/boot/dts/imx6qdl-rex.dtsi b/arch/arm/boot/dts/imx6qdl-rex.dtsi
index a503562..cacf593 100644
--- a/arch/arm/boot/dts/imx6qdl-rex.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-rex.dtsi
@@ -126,7 +126,7 @@
 	codec: sgtl5000@0a {
 		compatible = "fsl,sgtl5000";
 		reg = <0x0a>;
-		clocks = <&clks 201>;
+		clocks = <&clks IMX6QDL_CLK_CKO>;
 		VDDA-supply = <&reg_3p3v>;
 		VDDIO-supply = <&reg_3p3v>;
 	};