ghes_edac: Don't credit the same memory dimm twice

On my tests on a 4xE5-4650 CPU's system, the GHES
EDAC driver is called twice. As the SMBIOS DMI enumeration
call will seek for the entire DIMM sockets in the system, on
this machine, equipped with 128 GB of RAM, the memory is
displayed twice:

          +-----------------------+
          |    mc0    |    mc1    |
----------+-----------------------+
memory45: |  8192 MB  |  8192 MB  |
memory44: |     0 MB  |     0 MB  |
----------+-----------------------+
memory43: |     0 MB  |     0 MB  |
memory42: |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory41: |     0 MB  |     0 MB  |
memory40: |     0 MB  |     0 MB  |
----------+-----------------------+
memory39: |  8192 MB  |  8192 MB  |
memory38: |     0 MB  |     0 MB  |
----------+-----------------------+
memory37: |     0 MB  |     0 MB  |
memory36: |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory35: |     0 MB  |     0 MB  |
memory34: |     0 MB  |     0 MB  |
----------+-----------------------+
memory33: |  8192 MB  |  8192 MB  |
memory32: |     0 MB  |     0 MB  |
----------+-----------------------+
memory31: |     0 MB  |     0 MB  |
memory30: |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory29: |     0 MB  |     0 MB  |
memory28: |     0 MB  |     0 MB  |
----------+-----------------------+
memory27: |  8192 MB  |  8192 MB  |
memory26: |     0 MB  |     0 MB  |
----------+-----------------------+
memory25: |     0 MB  |     0 MB  |
memory24: |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory23: |     0 MB  |     0 MB  |
memory22: |     0 MB  |     0 MB  |
----------+-----------------------+
memory21: |  8192 MB  |  8192 MB  |
memory20: |     0 MB  |     0 MB  |
----------+-----------------------+
memory19: |     0 MB  |     0 MB  |
memory18: |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory17: |     0 MB  |     0 MB  |
memory16: |     0 MB  |     0 MB  |
----------+-----------------------+
memory15: |  8192 MB  |  8192 MB  |
memory14: |     0 MB  |     0 MB  |
----------+-----------------------+
memory13: |     0 MB  |     0 MB  |
memory12: |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory11: |     0 MB  |     0 MB  |
memory10: |     0 MB  |     0 MB  |
----------+-----------------------+
memory9:  |  8192 MB  |  8192 MB  |
memory8:  |     0 MB  |     0 MB  |
----------+-----------------------+
memory7:  |     0 MB  |     0 MB  |
memory6:  |  8192 MB  |  8192 MB  |
----------+-----------------------+
memory5:  |     0 MB  |     0 MB  |
memory4:  |     0 MB  |     0 MB  |
----------+-----------------------+
memory3:  |  8192 MB  |  8192 MB  |
memory2:  |     0 MB  |     0 MB  |
----------+-----------------------+
memory1:  |     0 MB  |     0 MB  |
memory0:  |  8192 MB  |  8192 MB  |
----------+-----------------------+

Total sum of 256 GB.

As there's no reliable way to credit DIMMS to the right memory
controller, just put everything on memory controller 0 (with should
always exist).

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>