The legacy edac ABI is going to be removed. Port the driver to use
and benefit from the new API functionality.

Cc: Olof Johansson <olof@lixom.net>
Cc: Egor Martovetsky <egor@pasemi.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>