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

This reverts commit d4dfa684941a21314b70593d01b0fc2167eebad4.

Change-Id: Id61ce69215505c3cf5d30ec2a7ec9127fb2554fc
diff --git a/src/backends/backendsCommon/IBackendInternal.hpp b/src/backends/backendsCommon/IBackendInternal.hpp
index a24b600..7e44dbd 100644
--- a/src/backends/backendsCommon/IBackendInternal.hpp
+++ b/src/backends/backendsCommon/IBackendInternal.hpp
@@ -4,8 +4,7 @@
 //
 #pragma once
 
-#include <armnn/IBackend.hpp>
-#include <memory>
+#include <armnn/Types.hpp>
 
 namespace armnn
 {
@@ -14,6 +13,8 @@
 class IBackendInternal : public IBackend
 {
 protected:
+    // Creation must be done through a specific
+    // backend interface.
     IBackendInternal() = default;
 
 public: