i7core_edac: Drop the edac_mce facility

Remove edac_mce pieces and use the normal MCE decoder notifier chain by
retaining the same functionality with considerably less code.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>