dt-bindings: freescale: Add bindings for the M4IF module

Add bindings for the M4IF module present on i.MX51.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/freescale/m4if.txt

+* Freescale Multi Master Multi Memory Interface (M4IF) module
+
+Required properties:
+- compatible : Should be "fsl,imx51-m4if"
+- reg : Address and length of the register set for the device
+
+Example:
+
+m4if: m4if@83fd8000 {
+	compatible = "fsl,imx51-m4if";
+	reg = <0x83fd8000 0x1000>;
+};