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

Change-Id: I477f52a9adf06ba3730f94d411399977fce0f98a
diff --git a/tests/framework/instruments/OpenCLTimer.cpp b/tests/framework/instruments/OpenCLTimer.cpp
index c443aad..fefc891 100644
--- a/tests/framework/instruments/OpenCLTimer.cpp
+++ b/tests/framework/instruments/OpenCLTimer.cpp
@@ -229,8 +229,9 @@
     return measurements;
 }
 
-template class OpenCLClock<true>;
-template class OpenCLClock<false>;
 } // namespace framework
 } // namespace test
 } // namespace arm_compute
+
+template class arm_compute::test::framework::OpenCLClock<true>;
+template class arm_compute::test::framework::OpenCLClock<false>;