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/L2NormalizationTestImpl.cpp b/src/backends/backendsCommon/test/layerTests/L2NormalizationTestImpl.cpp
index d67f7b6..4b16921 100644
--- a/src/backends/backendsCommon/test/layerTests/L2NormalizationTestImpl.cpp
+++ b/src/backends/backendsCommon/test/layerTests/L2NormalizationTestImpl.cpp
@@ -33,6 +33,7 @@
     const armnn::DataLayout layout,
     float epsilon = 1e-12f)
 {
+    boost::ignore_unused(memoryManager);
     const armnn::TensorInfo inputTensorInfo(inputOutputTensorShape, ArmnnType, scale, offset);
     const armnn::TensorInfo outputTensorInfo(inputOutputTensorShape, ArmnnType, outScale, outOffset);