EDAC, layerscape: Allow building for LS1021A

The LS1021A has a memory controller supported by this driver. It builds
just fine, and I've done some rudimentary testing using the error
injection facility, which suggests that it is indeed working.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Acked-by: York Sun <york.sun@nxp.com>
Cc: Alexander Stein <alexander.stein@systec-electronic.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20180220150912.2954-1-rasmus.villemoes@prevas.dk
Signed-off-by: Borislav Petkov <bp@suse.de>