i7core_edac: fix erroneous size of static array

Remove size from lookup arrays and mark them as const.

Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Niklas Söderlund <niso@kth.se>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>