IVGCVSW-4246 Clean build of LayerTests with -Wextra

Change-Id: If3d98e45a6e2fa8e1afd19a4052334335feacf63
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
diff --git a/src/backends/backendsCommon/test/layerTests/DepthToSpaceTestImpl.cpp b/src/backends/backendsCommon/test/layerTests/DepthToSpaceTestImpl.cpp
index 4e8c938..5e5cba3 100644
--- a/src/backends/backendsCommon/test/layerTests/DepthToSpaceTestImpl.cpp
+++ b/src/backends/backendsCommon/test/layerTests/DepthToSpaceTestImpl.cpp
@@ -30,6 +30,7 @@
     const float qScale = 1.0f,
     const int32_t qOffset = 0)
 {
+    boost::ignore_unused(memoryManager);
     if (descriptor.m_Parameters.m_DataLayout == armnn::DataLayout::NCHW)
     {
         PermuteTensorNhwcToNchw<float>(inputInfo, inputData);