edac: altera: Add EDAC support for Altera SDRAM Controller

[tthayer at altera.com]

This patch adds EDAC support for the Altera CycloneV and ArriaV
SoC SDRAM Controller.

[PATCHv3 1/3] dts: socfpga: Add bindings for Altera SoC SDRAM
[PATCHv3 2/3] dts: socfpga: Add bindings for Altera SoC SDRAM EDAC
[PATCHv3 3/3] edac: altera: Add EDAC support for Altera SDRAM