ARM: OMAP2+: Update GPMC and NAND DT binding documentation

Add additional details to the GPMC NAND documentation to clarify
what is needed to enable NAND DMA prefetch.
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

Documentation/devicetree/bindings/memory-controllers/omap-gpmc.txt

@@ -46,6 +46,10 @@ Required properties:
 			0 maps to GPMC_WAIT0 pin.
  - gpio-cells:		Must be set to 2
 
+Required properties when using NAND prefetch dma:
+ - dmas			GPMC NAND prefetch dma channel
+ - dma-names		Must be set to "rxtx"
+
 Timing properties for child nodes. All are optional and default to 0.
 
  - gpmc,sync-clk-ps:	Minimum clock period for synchronous mode, in picoseconds
@@ -137,7 +141,8 @@ Example for an AM33xx board:
 		ti,hwmods = "gpmc";
 		reg = <0x50000000 0x2000>;
 		interrupts = <100>;
-
+		dmas = <&edma 52 0>;
+		dma-names = "rxtx";
 		gpmc,num-cs = <8>;
 		gpmc,num-waitpins = <2>;
 		#address-cells = <2>;

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

@@ -39,7 +39,7 @@ Optional properties:
 
 		"prefetch-polled"	Prefetch polled mode (default)
 		"polled"		Polled mode, without prefetch
-		"prefetch-dma"		Prefetch enabled sDMA mode
+		"prefetch-dma"		Prefetch enabled DMA mode
 		"prefetch-irq"		Prefetch enabled irq mode
 
  - elm_id:	<deprecated> use "ti,elm-id" instead