ARM: dts: Modify SPI nodes according generic DMA DT bindings

This patch removes custom way of adding spi dma channels and
adds according to new generic DMA DT bindings.

Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

arch/arm/boot/dts/exynos5250.dtsi

@@ -211,8 +211,9 @@
 		compatible = "samsung,exynos4210-spi";
 		reg = <0x12d20000 0x100>;
 		interrupts = <0 66 0>;
-		tx-dma-channel = <&pdma0 5>; /* preliminary */
-		rx-dma-channel = <&pdma0 4>; /* preliminary */
+		dmas = <&pdma0 5
+			&pdma0 4>;
+		dma-names = "tx", "rx";
 		#address-cells = <1>;
 		#size-cells = <0>;
 	};
@@ -221,8 +222,9 @@
 		compatible = "samsung,exynos4210-spi";
 		reg = <0x12d30000 0x100>;
 		interrupts = <0 67 0>;
-		tx-dma-channel = <&pdma1 5>; /* preliminary */
-		rx-dma-channel = <&pdma1 4>; /* preliminary */
+		dmas = <&pdma1 5
+			&pdma1 4>;
+		dma-names = "tx", "rx";
 		#address-cells = <1>;
 		#size-cells = <0>;
 	};
@@ -231,8 +233,9 @@
 		compatible = "samsung,exynos4210-spi";
 		reg = <0x12d40000 0x100>;
 		interrupts = <0 68 0>;
-		tx-dma-channel = <&pdma0 7>; /* preliminary */
-		rx-dma-channel = <&pdma0 6>; /* preliminary */
+		dmas = <&pdma0 7
+			&pdma0 6>;
+		dma-names = "tx", "rx";
 		#address-cells = <1>;
 		#size-cells = <0>;
 	};