COMPMID-250 make BorderSize explicit and fix float value validation bug

Change-Id: I747fdef3b5ad83a9c00dc42796debe86b6cd972e
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/78686
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Moritz Pflanzer <moritz.pflanzer@arm.com>
diff --git a/src/core/CL/kernels/CLBox3x3Kernel.cpp b/src/core/CL/kernels/CLBox3x3Kernel.cpp
index e113d30..0299f62 100644
--- a/src/core/CL/kernels/CLBox3x3Kernel.cpp
+++ b/src/core/CL/kernels/CLBox3x3Kernel.cpp
@@ -37,7 +37,7 @@
 
 BorderSize CLBox3x3Kernel::border_size() const
 {
-    return 1;
+    return BorderSize(1);
 }
 
 void CLBox3x3Kernel::configure(const ICLTensor *input, ICLTensor *output, bool border_undefined)