ARM: dts: imx6: use correct mclk frequency for audio codec

The reference clock for the SGTL5000 is generated by a 26MHz crystal
oscillator on the Ka-Ro electronics STK5 eval kits. Use the correct
frequency setting in DTB.
Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6qdl-tx6.dtsi

@@ -41,7 +41,7 @@ mclk: clock@0 {
 			compatible = "fixed-clock";
 			reg = <0>;
 			#clock-cells = <0>;
-			clock-frequency = <27000000>;
+			clock-frequency = <26000000>;
 		};
 	};