Correct Copyright dates

Some dates where wrongly changed to 2021 when
we moved some files over to the new API.

Resolves: COMPMID-4312

Change-Id: I4aae61f7f4d01f69fcb664b0f71b9e508bd1f5f8
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5361
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Manuel Bottini <manuel.bottini@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/cpu/kernels/CpuDequantizationKernel.cpp b/src/core/cpu/kernels/CpuDequantizationKernel.cpp
index cb77d36..171e132 100644
--- a/src/core/cpu/kernels/CpuDequantizationKernel.cpp
+++ b/src/core/cpu/kernels/CpuDequantizationKernel.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Arm Limited.
+ * Copyright (c) 2017-2021 Arm Limited.
  *
  * SPDX-License-Identifier: MIT
  *