ARM: dts: exynos: Add #sound-dai-cells property to exynos5250 i2s nodes

The #sound-dai-cells property may be required to reference the CPU DAI
properly. This change is required for Snow HDMI audio.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos5250.dtsi

@@ -499,6 +499,7 @@ &pdma0 9
 			pinctrl-0 = <&i2s0_bus>;
 			power-domains = <&pd_mau>;
 			#clock-cells = <1>;
+			#sound-dai-cells = <1>;
 		};
 
 		i2s1: i2s@12d60000 {
@@ -513,6 +514,7 @@ i2s1: i2s@12d60000 {
 			pinctrl-names = "default";
 			pinctrl-0 = <&i2s1_bus>;
 			power-domains = <&pd_mau>;
+			#sound-dai-cells = <1>;
 		};
 
 		i2s2: i2s@12d70000 {
@@ -527,6 +529,7 @@ i2s2: i2s@12d70000 {
 			pinctrl-names = "default";
 			pinctrl-0 = <&i2s2_bus>;
 			power-domains = <&pd_mau>;
+			#sound-dai-cells = <1>;
 		};
 
 		usb_dwc3 {