arm64: dts: n5x: add sdr edac support

The N5X platform has the Synopsys DDR controller the includes an EDAC
controller. Add the entry for the controller in the DTS file instead of
the base Agilex DTSI because the base Agilex does not have the
controller.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>