EDAC, amd64: Don't treat ECC disabled as failure

Having ECC disabled on a node doesn't necessarily mean that it's
disabled for the entire system. So let's return a non-failing code when
ECC is disabled on a node. This way we can skip initialization for the
node but still continue with the remaining nodes.

After probing all instances, make sure we have at least one MC device
allocated.

This issue is seen and fix tested on Fam15h and Fam17h MCM systems.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1485537863-2707-8-git-send-email-Yazen.Ghannam@amd.com
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/edac/amd64_edac.c

@@ -3336,7 +3336,7 @@ static int probe_one_instance(unsigned int nid)
 	ecc_stngs[nid] = s;
 
 	if (!ecc_enabled(F3, nid)) {
-		ret = -ENODEV;
+		ret = 0;
 
 		if (!ecc_enable_override)
 			goto err_enable;
@@ -3465,6 +3465,11 @@ static int __init amd64_edac_init(void)
 		}
 	}
 
+	if (!edac_has_mcs()) {
+		err = -ENODEV;
+		goto err_pci;
+	}
+
 	/* register stuff with EDAC MCE */
 	if (report_gart_errors)
 		amd_report_gart_errors(true);