Fix OperationalStatus disappear problem

Fix the problem that after BMC reboot, there will be no OperationalStatus
path in PSUSensor.

Tested:
Reboot BMC, /xyz/openbmc_project/State/Decorator/PSUx_OperationalStatus should
show in PSUSensor D-Bus interface. And Power Unit Redundancy should work
correctly.

Signed-off-by: Cheng C Yang <cheng.c.yang@linux.intel.com>
Change-Id: I1750ba25c9d6ecbebeebc8447567581ba99266cf
diff --git a/src/PSUSensorMain.cpp b/src/PSUSensorMain.cpp
index d66e5be..400c514 100644
--- a/src/PSUSensorMain.cpp
+++ b/src/PSUSensorMain.cpp
@@ -149,6 +149,7 @@
 
     // TODO may need only modify the ones that need to be changed.
     sensors.clear();
+    combineEvents.clear();
     for (const char* type : sensorTypes)
     {
         if (!getSensorConfiguration(type, dbusConnection, sensorConfigs,
@@ -433,6 +434,7 @@
         }
 
         // OperationalStatus event
+        combineEvents[*psuName + "OperationalStatus"] = nullptr;
         combineEvents[*psuName + "OperationalStatus"] =
             std::make_unique<PSUCombineEvent>(
                 objectServer, io, *psuName, eventPathList, "OperationalStatus");