IVGCVSW-4483 Removes boost::polymorphic_pointer_downcast

 * replace boost::polymorphic_pointer_downcast by PolymorphicPointerDowncast
 * replaced/removed includes

Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Change-Id: I0ef934a3804cf05e4c38dec6c4ec49c76111a302
diff --git a/src/backends/cl/workloads/ClDequantizeWorkload.cpp b/src/backends/cl/workloads/ClDequantizeWorkload.cpp
index eca795d..eb63900 100644
--- a/src/backends/cl/workloads/ClDequantizeWorkload.cpp
+++ b/src/backends/cl/workloads/ClDequantizeWorkload.cpp
@@ -7,6 +7,7 @@
 #include "ClWorkloadUtils.hpp"
 
 #include <aclCommon/ArmComputeTensorUtils.hpp>
+#include <armnn/utility/PolymorphicDowncast.hpp>
 #include <backendsCommon/CpuTensorHandle.hpp>
 
 #include <arm_compute/core/Types.h>
@@ -14,8 +15,6 @@
 #include <cl/ClLayerSupport.hpp>
 #include <cl/ClTensorHandle.hpp>
 
-#include <boost/polymorphic_pointer_cast.hpp>
-
 namespace armnn
 {
 using namespace armcomputetensorutils;
@@ -34,10 +33,10 @@
 {
     m_Data.ValidateInputsOutputs("ClDequantizeWorkload", 1, 1);
 
-    arm_compute::ICLTensor& input = boost::polymorphic_pointer_downcast<IClTensorHandle>(
+    arm_compute::ICLTensor& input = armnn::PolymorphicPointerDowncast<IClTensorHandle>(
             m_Data.m_Inputs[0])->GetTensor();
 
-    arm_compute::ICLTensor& output = boost::polymorphic_pointer_downcast<IClTensorHandle>(
+    arm_compute::ICLTensor& output = armnn::PolymorphicPointerDowncast<IClTensorHandle>(
             m_Data.m_Outputs[0])->GetTensor();
 
     m_Layer.reset(new arm_compute::CLDequantizationLayer());