ARM: OMAP2+: gpmc: add DT bindings for OneNAND

This patch adds device tree bindings for OMAP OneNAND devices.
Tested on an OMAP3 3430 IGEPv2 board.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Documentation/devicetree/bindings/mtd/gpmc-onenand.txt

@@ -0,0 +1,43 @@
+Device tree bindings for GPMC connected OneNANDs
+
+GPMC connected OneNAND (found on OMAP boards) are represented as child nodes of
+the GPMC controller with a name of "onenand".
+
+All timing relevant properties as well as generic gpmc child properties are
+explained in a separate documents - please refer to
+Documentation/devicetree/bindings/bus/ti-gpmc.txt
+
+Required properties:
+
+ - reg:			The CS line the peripheral is connected to
+
+Optional properties:
+
+ - dma-channel:		DMA Channel index
+
+For inline partiton table parsing (optional):
+
+ - #address-cells: should be set to 1
+ - #size-cells: should be set to 1
+
+Example for an OMAP3430 board:
+
+	gpmc: gpmc@6e000000 {
+		compatible = "ti,omap3430-gpmc";
+		ti,hwmods = "gpmc";
+		reg = <0x6e000000 0x1000000>;
+		interrupts = <20>;
+		gpmc,num-cs = <8>;
+		gpmc,num-waitpins = <4>;
+		#address-cells = <2>;
+		#size-cells = <1>;
+
+		onenand@0 {
+			reg = <0 0 0>; /* CS0, offset 0 */
+
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			/* partitions go here */
+		};
+	};