Remove inclusion of ArmNN.hpp where it is unnecessary.

Signed-off-by: Matthew Bentham <Matthew.Bentham@arm.com>
Change-Id: Idb583f8de4470eefb47c90189cd3c90e74e0440a
diff --git a/src/backends/reference/workloads/LogSoftmax.hpp b/src/backends/reference/workloads/LogSoftmax.hpp
index 2e38399..6d46cb9 100644
--- a/src/backends/reference/workloads/LogSoftmax.hpp
+++ b/src/backends/reference/workloads/LogSoftmax.hpp
@@ -5,10 +5,11 @@
 
 #pragma once
 
-#include "BaseIterator.hpp"
-
+#include <armnn/Descriptors.hpp>
 #include <armnn/Tensor.hpp>
 
+#include "BaseIterator.hpp"
+
 namespace armnn
 {