dt-bindings: memory: Add pl353 smc controller devicetree binding information

Add pl353 static memory controller devicetree binding information.
Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt

+Device tree bindings for ARM PL353 static memory controller
+
+PL353 static memory controller supports two kinds of memory
+interfaces.i.e NAND and SRAM/NOR interfaces.
+The actual devices are instantiated from the child nodes of pl353 smc node.
+
+Required properties:
+- compatible		: Should be "arm,pl353-smc-r2p1", "arm,primecell".
+- reg			: Controller registers map and length.
+- clock-names		: List of input clock names - "memclk", "apb_pclk"
+			  (See clock bindings for details).
+- clocks		: Clock phandles (see clock bindings for details).
+- address-cells		: Must be 2.
+- size-cells		: Must be 1.
+
+Child nodes:
+ For NAND the "arm,pl353-nand-r2p1" and for NOR the "cfi-flash" drivers are
+supported as child nodes.
+
+for NAND partition information please refer the below file
+Documentation/devicetree/bindings/mtd/partition.txt
+
+Example:
+	smcc: memory-controller@e000e000
+			compatible = "arm,pl353-smc-r2p1", "arm,primecell";
+			clock-names = "memclk", "apb_pclk";
+			clocks = <&clkc 11>, <&clkc 44>;
+			reg = <0xe000e000 0x1000>;
+			#address-cells = <2>;
+			#size-cells = <1>;
+			ranges = <0x0 0x0 0xe1000000 0x1000000 //Nand CS Region
+				  0x1 0x0 0xe2000000 0x2000000 //SRAM/NOR CS Region
+				  0x2 0x0 0xe4000000 0x2000000>; //SRAM/NOR CS Region
+			nand_0: flash@e1000000 {
+				compatible = "arm,pl353-nand-r2p1"
+				reg = <0 0 0x1000000>;
+				(...)
+			};
+			nor0: flash@e2000000 {
+				compatible = "cfi-flash";
+				reg = <1 0 0x2000000>;
+			};
+			nor1: flash@e4000000 {
+				compatible = "cfi-flash";
+				reg = <2 0 0x2000000>;
+			};
+	};