log_services: don't replace res.jsonValue

There were places where res.jsonValue was being replaced by assigning a
new object. This changes those to use res.jsonValue.update() to replace
the contents instead of the entire object.

Tested:
Confirmed that individual event, journal, and crashdump entries can
still be retrieved.

Change-Id: I8a0885530af58393d4b90fe15390db8c3af02994
Signed-off-by: Jason M. Bills <jason.m.bills@intel.com>
diff --git a/redfish-core/lib/log_services.hpp b/redfish-core/lib/log_services.hpp
index 0a16866..6fee6ed 100644
--- a/redfish-core/lib/log_services.hpp
+++ b/redfish-core/lib/log_services.hpp
@@ -1289,7 +1289,7 @@
                         messages::internalError(asyncResp->res);
                         return;
                     }
-                    asyncResp->res.jsonValue = std::move(bmcLogEntry);
+                    asyncResp->res.jsonValue.update(bmcLogEntry);
                     return;
                 }
             }
@@ -2315,7 +2315,7 @@
             messages::internalError(asyncResp->res);
             return;
         }
-        asyncResp->res.jsonValue = std::move(bmcJournalLogEntry);
+        asyncResp->res.jsonValue.update(bmcJournalLogEntry);
         });
 }
 
@@ -2801,7 +2801,7 @@
         }
         else
         {
-            logEntryJson = logEntry;
+            logEntryJson.update(logEntry);
         }
     };
     crow::connections::systemBus->async_method_call(