Fix elapsed time calc for hipEventElapsedTime

If the start and stop events have same command internally
then measure command end to command start
Change-Id: Ie70cfa37c06c06573f0ed58dab2bbe4434c1724b

rocclr/hip_event.cpp

@@ -90,9 +90,15 @@ hipError_t Event::elapsedTime(Event& eStop, float& ms) {
     return hipErrorNotReady;
   }
 
-  ms = static_cast<float>(static_cast<int64_t>(eStop.event_->profilingInfo().end_ -
+  // For certain HIP Api's that take start and stop event
+  // the command is the same
+  if (event_ == eStop.event_) {
+    ms = static_cast<float>(static_cast<int64_t>(eStop.event_->profilingInfo().end_ -
+                          event_->profilingInfo().start_))/1000000.f;
+  } else {
+    ms = static_cast<float>(static_cast<int64_t>(eStop.event_->profilingInfo().end_ -
                           event_->profilingInfo().end_))/1000000.f;
-
+  }
   return hipSuccess;
 }