amd64_edac: convert sysfs logic to use struct device

Now that the EDAC core supports struct device, there's no sense
on having any logic at the EDAC core to simulate it. So, instead
of adding such logic there, change the logic at amd64_edac to
use it.

Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>