IVGCVSW-1998 : replace Compute enum in LayerSupport free functions

!android-nn-driver:153490

Change-Id: I1c2a5f942e3a1c3626e093c90545ca27c64ba5e8
diff --git a/src/backends/cl/ClBackend.hpp b/src/backends/cl/ClBackend.hpp
index b927db4..1a99b76 100644
--- a/src/backends/cl/ClBackend.hpp
+++ b/src/backends/cl/ClBackend.hpp
@@ -16,7 +16,8 @@
     ClBackend()  = default;
     ~ClBackend() = default;
 
-    const BackendId& GetId() const override;
+    static const BackendId& GetIdStatic();
+    const BackendId& GetId() const override { return GetIdStatic(); }
 
     const ILayerSupport& GetLayerSupport() const override;