Make CLArithmeticAddition kernel and function state-less

Resolves COMPMID-4006

Change-Id: Iddc32b0b250142aac9a4a7b9dc0eef462d196025
Signed-off-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/4913
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Sang-Hoon Park <sang-hoon.park@arm.com>
diff --git a/src/core/KernelTypes.h b/src/core/KernelTypes.h
index 12e6bc9..a32f5db 100644
--- a/src/core/KernelTypes.h
+++ b/src/core/KernelTypes.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020 Arm Limited.
+ * Copyright (c) 2020-2021 Arm Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -26,8 +26,6 @@
 
 namespace arm_compute
 {
-namespace kernels
-{
 /** List of supported logical operations */
 enum class LogicalOperation
 {
@@ -36,6 +34,5 @@
     Or,      /**< Logical Or || */
     Not,     /**< Logical Not ! */
 };
-} // namespace kernels
 } // namespace arm_compute
 #endif /* ARM_COMPUTE_KERNEL_TYPES_H */