Fix incorrect copyright notices

 * Updated headers that were missing a copyright notice.
 * Reverted years that were incorrectly updated.

Signed-off-by: Matthew Sloyan <matthew.sloyan@arm.com>
Change-Id: I65842f1e9b9fd5654563edd5090133cb3c89fecc
diff --git a/src/armnn/layers/ReduceLayer.cpp b/src/armnn/layers/ReduceLayer.cpp
index e411996..ebee213 100644
--- a/src/armnn/layers/ReduceLayer.cpp
+++ b/src/armnn/layers/ReduceLayer.cpp
@@ -1,5 +1,6 @@
 //
-// Copyright © 2020-2023 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2023 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 
diff --git a/src/armnn/layers/ReduceLayer.hpp b/src/armnn/layers/ReduceLayer.hpp
index 24f19f8..4747d28 100644
--- a/src/armnn/layers/ReduceLayer.hpp
+++ b/src/armnn/layers/ReduceLayer.hpp
@@ -1,5 +1,6 @@
 //
-// Copyright © 2020-2023 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2023 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 #pragma once
diff --git a/src/armnnDeserializer/test/DeserializeReduceSum.cpp b/src/armnnDeserializer/test/DeserializeReduceSum.cpp
index 1d72b0f..0405b0e 100644
--- a/src/armnnDeserializer/test/DeserializeReduceSum.cpp
+++ b/src/armnnDeserializer/test/DeserializeReduceSum.cpp
@@ -1,5 +1,6 @@
 //
 // Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2021 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 
diff --git a/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.cpp b/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.cpp
index bda8870..d45ae05 100644
--- a/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.cpp
+++ b/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.cpp
@@ -1,5 +1,6 @@
 //
 // Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2021-2022 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 
diff --git a/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.hpp b/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.hpp
index 283f0df..28c7fe6 100644
--- a/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.hpp
+++ b/src/backends/backendsCommon/test/layerTests/ReduceSumTestImpl.hpp
@@ -1,5 +1,6 @@
 //
 // Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2021 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 
diff --git a/src/backends/reference/workloads/RefReduceWorkload.cpp b/src/backends/reference/workloads/RefReduceWorkload.cpp
index e7d05ca..b4b8952 100644
--- a/src/backends/reference/workloads/RefReduceWorkload.cpp
+++ b/src/backends/reference/workloads/RefReduceWorkload.cpp
@@ -1,5 +1,6 @@
 //
-// Copyright © 2022 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2021-2022 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //
 
diff --git a/src/backends/reference/workloads/RefReduceWorkload.hpp b/src/backends/reference/workloads/RefReduceWorkload.hpp
index 2611932..064d71e 100644
--- a/src/backends/reference/workloads/RefReduceWorkload.hpp
+++ b/src/backends/reference/workloads/RefReduceWorkload.hpp
@@ -1,5 +1,6 @@
 //
-// Copyright © 2022 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2020 Samsung Electronics Co Ltd and Contributors. All rights reserved.
+// Copyright © 2021-2022 Arm Ltd and Contributors. All rights reserved.
 // SPDX-License-Identifier: MIT
 //