COMPMID-1777 Fixed compilation error due to templates being instantiated inside the namespace

Change-Id: I477f52a9adf06ba3730f94d411399977fce0f98a
diff --git a/tests/framework/instruments/WallClockTimer.cpp b/tests/framework/instruments/WallClockTimer.cpp
index f309efc..b5dc864 100644
--- a/tests/framework/instruments/WallClockTimer.cpp
+++ b/tests/framework/instruments/WallClockTimer.cpp
@@ -75,9 +75,9 @@
     return measurements;
 }
 
-template class WallClock<true>;
-template class WallClock<false>;
-
 } // namespace framework
 } // namespace test
 } // namespace arm_compute
+
+template class arm_compute::test::framework::WallClock<true>;
+template class arm_compute::test::framework::WallClock<false>;