Revert "IVGCVSW-2056 + IVGCVSW-2064 : move ClContextControl to the ClBackend"

This reverts commit d4dfa684941a21314b70593d01b0fc2167eebad4.

Change-Id: Id61ce69215505c3cf5d30ec2a7ec9127fb2554fc
diff --git a/src/backends/cl/ClBackend.hpp b/src/backends/cl/ClBackend.hpp
index 381d808..223aeb3 100644
--- a/src/backends/cl/ClBackend.hpp
+++ b/src/backends/cl/ClBackend.hpp
@@ -12,8 +12,8 @@
 class ClBackend : public IBackendInternal
 {
 public:
-    ClBackend() = default;
-    ~ClBackend() override = default;
+    ClBackend()  = default;
+    ~ClBackend() = default;
 
     static const BackendId& GetIdStatic();
     const BackendId& GetId() const override { return GetIdStatic(); }