EDAC/amd64: Set grain per DIMM

The following commit introduced a warning on error reports without a
non-zero grain value.

  3724ace5 ("EDAC/mc: Fix grain_bits calculation")

The amd64_edac_mod module does not provide a value, so the warning will
be given on the first reported memory error.

Set the grain per DIMM to cacheline size (64 bytes). This is the current
recommendation.

Fixes: 3724ace5 ("EDAC/mc: Fix grain_bits calculation")
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Robert Richter <rrichter@marvell.com>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20191022203448.13962-7-Yazen.Ghannam@amd.com

drivers/edac/amd64_edac.c

@@ -2936,6 +2936,7 @@ static int init_csrows_df(struct mem_ctl_info *mci)
 			dimm->mtype = pvt->dram_type;
 			dimm->edac_mode = edac_mode;
 			dimm->dtype = dev_type;
+			dimm->grain = 64;
 		}
 	}
 
@@ -3012,6 +3013,7 @@ static int init_csrows(struct mem_ctl_info *mci)
 			dimm = csrow->channels[j]->dimm;
 			dimm->mtype = pvt->dram_type;
 			dimm->edac_mode = edac_mode;
+			dimm->grain = 64;
 		}
 	}