Fix SessionService odata.id

SessionService had the wrong @odata.id.
Redfish-Service-Validator found this.

Change-Id: Idf67b46b69b6ad770062ea3146996d100c424eea
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/redfish-core/lib/service_root.hpp b/redfish-core/lib/service_root.hpp
index cbe3f11..3b2aae5 100644
--- a/redfish-core/lib/service_root.hpp
+++ b/redfish-core/lib/service_root.hpp
@@ -56,7 +56,7 @@
             {"@odata.id", "/redfish/v1/JsonSchemas"}};
         res.jsonValue["Managers"] = {{"@odata.id", "/redfish/v1/Managers"}};
         res.jsonValue["SessionService"] = {
-            {"@odata.id", "/redfish/v1/UpdateService"}};
+            {"@odata.id", "/redfish/v1/SessionService"}};
         res.jsonValue["Systems"] = {{"@odata.id", "/redfish/v1/Systems"}};
         res.jsonValue["Registries"] = {{"@odata.id", "/redfish/v1/Registries"}};