amd64_edac: add F10h-and-later methods-p1

Borislav:

Fail f10_early_channel_count() if error encountered while reading a NB
register since those cached register contents are accessed afterwards.

- fix/cleanup comments
- fix function return value patterns
- cleanup debug calls

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