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/LeNet5Fixture.h b/tests/benchmark/fixtures/LeNet5Fixture.h
index 5108042..03e426d 100644
--- a/tests/benchmark/fixtures/LeNet5Fixture.h
+++ b/tests/benchmark/fixtures/LeNet5Fixture.h
@@ -33,6 +33,8 @@
 {
 namespace test
 {
+namespace benchmark
+{
 template <typename TensorType,
           typename Accessor,
           typename ActivationLayerFunction,
@@ -76,6 +78,7 @@
              SoftmaxLayerFunction>
              network{};
 };
+} // namespace benchmark
 } // namespace test
 } // namespace arm_compute
 #endif /* ARM_COMPUTE_TEST_LENET5FIXTURE */