arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries.

Add the Altera SDRAM EDAC bindings and device tree changes to the Altera SoC
project.

There was a discussion thread on whether this driver should be an mfd driver
or just make use of syscon, which is already a mfd. Ultimately, the
decision to use a simple syscon interface was reached.[1]

[1] https://lkml.org/lkml/2014/7/30/514Signed-off-by: NThor Thayer <tthayer@opensource.altera.com>
Acked-by: NPavel Machek <pavel@denx.de>
[dinguyen] cleaned-up commit header and remove version history.
Signed-off-by: NDinh Nguyen <dinguyen@opensource.altera.com>

Documentation/devicetree/bindings/arm/altera/socfpga-sdram-edac.txt

+Altera SOCFPGA SDRAM Error Detection & Correction [EDAC]
+The EDAC accesses a range of registers in the SDRAM controller.
+
+Required properties:
+- compatible : should contain "altr,sdram-edac";
+- altr,sdr-syscon : phandle of the sdr module
+- interrupts : Should contain the SDRAM ECC IRQ in the
+	appropriate format for the IRQ controller.
+
+Example:
+	sdramedac {
+		compatible = "altr,sdram-edac";
+		altr,sdr-syscon = <&sdr>;
+		interrupts = <0 39 4>;
+	};

arch/arm/boot/dts/socfpga.dtsi

@@ -607,6 +607,17 @@
 			};
 		};
 
+		sdr: sdr@ffc25000 {
+			compatible = "syscon";
+			reg = <0xffc25000 0x1000>;
+		};
+
+		sdramedac {
+			compatible = "altr,sdram-edac";
+			altr,sdr-syscon = <&sdr>;
+			interrupts = <0 39 4>;
+		};
+
 		L2: l2-cache@fffef000 {
 			compatible = "arm,pl310-cache";
 			reg = <0xfffef000 0x1000>;