Make sure that gtpin callbacks are not executed in enqueue path.

-This is to make sure those functions are not called when gtpin is not used
-This preserves CPU instruction cache pollution.
-Our enqueue path needs to be as thin as possible, even with this small change
there is visible gain in ULT execution time.

Change-Id: I44cc2144754cda95ca1fe058184cd8a151b8d35c

runtime/command_stream/command_stream_receiver.cpp

@@ -193,7 +193,9 @@ bool CommandStreamReceiver::waitForCompletionWithTimeout(bool enableTimeout, int
         }
     }
     if (*getTagAddress() >= taskCountToWait) {
-        gtpinNotifyTaskCompletion(taskCountToWait);
+        if (gtpinIsGTPinInitialized()) {
+            gtpinNotifyTaskCompletion(taskCountToWait);
+        }
         return true;
     }
     return false;