ARM: tegra: nexus7: Add missing clock binding into sound node

A recent rt5640 codec update requires mclk definition in the
device tree. Without mclk defined sound will not work.
Signed-off-by: Robert Eckelmann <longnoserob@gmail.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/nvidia/tegra30-asus-nexus7-grouper-common.dtsi

@@ -915,6 +915,9 @@ rt5640: audio-codec@1c {
 			reg = <0x1c>;
 
 			realtek,dmic1-data-pin = <1>;
+
+			clocks = <&tegra_pmc TEGRA_PMC_CLK_OUT_1>;
+			clock-names = "mclk";
 		};
 
 		nct72: temperature-sensor@4c {