Documentation: dt: edac: Move Altera SOCFPGA EDAC file

Move the Altera SOCFPGA EDAC file from bindings/arm/altera to
bindings/edac.

Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
Requested-by: Rob Herring <robh@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1525203036-21774-1-git-send-email-thor.thayer@linux.intel.com
Signed-off-by: Borislav Petkov <bp@suse.de>