amd64_edac: Simplify ECC override handling

No need for clearing ecc_enable_override and checking it in two places.
Instead, simply check it during probing and act accordingly. Also,
rename the flag bitfields according to the functionality they actually
represent. What is more, make sure original BIOS ECC settings are
restored when the module is unloaded.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
diff --git a/drivers/edac/amd64_edac.h b/drivers/edac/amd64_edac.h
index 41bc561..0d4bf56 100644
--- a/drivers/edac/amd64_edac.h
+++ b/drivers/edac/amd64_edac.h
@@ -487,7 +487,8 @@
 	/* misc settings */
 	struct flags {
 		unsigned long cf8_extcfg:1;
-		unsigned long ecc_report:1;
+		unsigned long nb_mce_enable:1;
+		unsigned long nb_ecc_prev:1;
 	} flags;
 };