MXS: Implement DMA support into mxs-i2c

This patch implements DMA support into mxs-i2c. DMA transfers are now enabled
via DT. The DMA operation is enabled by default.

Signed-off-by: Marek Vasut <marex@denx.de>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>

[wsa: rebased to 3.6-rc7]

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index 3fa6d19..ba8227e 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -661,6 +661,7 @@
 				reg = <0x80058000 0x2000>;
 				interrupts = <111 68>;
 				clock-frequency = <100000>;
+				fsl,i2c-dma-channel = <6>;
 				status = "disabled";
 			};
 
@@ -671,6 +672,7 @@
 				reg = <0x8005a000 0x2000>;
 				interrupts = <110 69>;
 				clock-frequency = <100000>;
+				fsl,i2c-dma-channel = <7>;
 				status = "disabled";
 			};