COMPMID-418 Add check and fix comments after preprocessor conditions

Change-Id: I1353fd652ee180e3931e58b4ce13d651a48c7e2c
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/79567
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Moritz Pflanzer <moritz.pflanzer@arm.com>
diff --git a/src/core/NEON/kernels/NECannyEdgeKernel.cpp b/src/core/NEON/kernels/NECannyEdgeKernel.cpp
index 85a2cd5..26df6f6 100644
--- a/src/core/NEON/kernels/NECannyEdgeKernel.cpp
+++ b/src/core/NEON/kernels/NECannyEdgeKernel.cpp
@@ -787,7 +787,7 @@
 
     INEKernel::configure(win);
 }
-#endif
+#endif /* ARM_COMPUTE_ENABLE_FP16 */
 
 namespace
 {