arm64: dts: imx8mm-nitrogen-r2: fix WM8960 clock name

The WM8960 Linux driver expects the clock to be named "mclk".  Otherwise
the clock will be ignored and not prepared/enabled by the driver.

Fixes: 40ba2ed ("arm64: dts: imx8mm-nitrogen-r2: add audio")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: krzk

arch/arm64/boot/dts/freescale/imx8mm-nitrogen-r2.dts

@@ -247,7 +247,7 @@
 		compatible = "wlf,wm8960";
 		reg = <0x1a>;
 		clocks = <&clk IMX8MM_CLK_SAI1_ROOT>;
-		clock-names = "mclk1";
+		clock-names = "mclk";
 		wlf,shared-lrclk;
 		#sound-dai-cells = <0>;
 	};