IVGCVSW-2211 Maximum operator support (CL)

   * Added CLMaximumWorkload implementation
   * Added CL unit tests

Change-Id: I922c83fe25d17be21a5d0f4e861038463cb09789
diff --git a/src/backends/cl/ClWorkloadFactory.cpp b/src/backends/cl/ClWorkloadFactory.cpp
index 942defb..37d9b31 100644
--- a/src/backends/cl/ClWorkloadFactory.cpp
+++ b/src/backends/cl/ClWorkloadFactory.cpp
@@ -299,7 +299,7 @@
 std::unique_ptr<IWorkload> ClWorkloadFactory::CreateMaximum(const MaximumQueueDescriptor& descriptor,
                                                             const WorkloadInfo& info) const
 {
-    return MakeWorkload<NullWorkload, NullWorkload>(descriptor, info);
+    return MakeWorkload<ClMaximumWorkload>(descriptor, info);
 }
 
 std::unique_ptr<IWorkload> ClWorkloadFactory::CreateMean(const MeanQueueDescriptor& descriptor,