IVGCVSW-4246 Clean build of backends with -Wextra

Change-Id: I9e8d5576b3ec04c871785d5f2f9545bf1136e59b
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
diff --git a/src/backends/reference/workloads/Dequantize.cpp b/src/backends/reference/workloads/Dequantize.cpp
index fafc03e..4025e8d 100644
--- a/src/backends/reference/workloads/Dequantize.cpp
+++ b/src/backends/reference/workloads/Dequantize.cpp
@@ -5,6 +5,7 @@
 
 #include "Dequantize.hpp"
 
+#include <boost/core/ignore_unused.hpp>
 namespace armnn
 {
 
@@ -13,6 +14,7 @@
                 const TensorInfo& inputInfo,
                 const TensorInfo& outputInfo)
 {
+    boost::ignore_unused(outputInfo);
     BOOST_ASSERT(inputInfo.GetNumElements() == outputInfo.GetNumElements());
     for (unsigned int i = 0; i < inputInfo.GetNumElements(); i++)
     {