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/CL/NormalizationLayer.cpp b/tests/benchmark/CL/NormalizationLayer.cpp
index 75a98b6..9ee5041 100644
--- a/tests/benchmark/CL/NormalizationLayer.cpp
+++ b/tests/benchmark/CL/NormalizationLayer.cpp
@@ -38,6 +38,8 @@
 {
 namespace test
 {
+namespace benchmark
+{
 namespace
 {
 const auto data_types = framework::dataset::make("DataType", { DataType::F16, DataType::F32 });
@@ -69,5 +71,6 @@
                                                             framework::dataset::make("Batches", { 4, 8 })));
 TEST_SUITE_END()
 TEST_SUITE_END()
+} // namespace benchmark
 } // namespace test
 } // namespace arm_compute