Fix enum_attrs.json error

a87190f145a193bb3d8aa55e3a82ebf65599d7d7 introduced a
syntax error in json.

This commit would fix it.

Tested: enabled OEM-IBM and built pldm successfully and
parse enum_attrs.json passed.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: If0f66d5463502c1bb2e1228304e0efc082e7a727
diff --git a/oem/ibm/configurations/bios/enum_attrs.json b/oem/ibm/configurations/bios/enum_attrs.json
index 2f84e23..35cc82d 100644
--- a/oem/ibm/configurations/bios/enum_attrs.json
+++ b/oem/ibm/configurations/bios/enum_attrs.json
@@ -285,7 +285,7 @@
          ],
          "default_values":[
             "Enabled"
-         },
+         ],
          "helpText" : "Specifies if the memory mirroring is enabled for the current IPL. Do not set this attribute directly; set hb_mirror_memory_mode instead.",
          "displayName" : "Mirror Memory Mode (current)"
       }