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/2014/7/30/514

Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
Acked-by: Pavel Machek <pavel@denx.de>
[dinguyen] cleaned-up commit header and remove version history.
Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>

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>;