UBI: print a message if ECH is corrupted and VIDH is ok

If the EC header is corrupted, but the VID header is OK, UBI accepts the
PEB and treats it as "used". However, generally this should not happen.
Print a warning if this happens.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/scan.c

@@ -864,7 +864,9 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
 		}
 	}
 
-	/* Both UBI headers seem to be fine */
+	if (ec_corr)
+		ubi_warn("valid VID header but corrupted EC header at PEB %d",
+			 pnum);
 	err = ubi_scan_add_used(ubi, si, pnum, ec, vidh, bitflips);
 	if (err)
 		return err;