COMPMID-959 Add benchmark namespace in benchmark tests

Change-Id: Ieef1c5380bff1c019af0203fb7e4734f48a2fb63
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/113499
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
diff --git a/tests/benchmark/fixtures/PoolingLayerFixture.h b/tests/benchmark/fixtures/PoolingLayerFixture.h
index 88edea3..a7deb75 100644
--- a/tests/benchmark/fixtures/PoolingLayerFixture.h
+++ b/tests/benchmark/fixtures/PoolingLayerFixture.h
@@ -34,6 +34,8 @@
 {
 namespace test
 {
+namespace benchmark
+{
 /** Fixture that can be used for NEON and CL */
 template <typename TensorType, typename Function, typename Accessor>
 class PoolingLayerFixture : public framework::Fixture
@@ -81,6 +83,7 @@
     TensorType dst{};
     Function   pool_layer{};
 };
+} // namespace benchmark
 } // namespace test
 } // namespace arm_compute
 #endif /* ARM_COMPUTE_TEST_POOLINGLAYERFIXTURE */