Update include/ck/tensor_operation/gpu/device/device_grouped_gemm_multi_abd_fixed_nk.hpp

Co-authored-by: Bartłomiej Kocot <barkocot@amd.com>

include/ck/tensor_operation/gpu/device/device_grouped_gemm_multi_abd_fixed_nk.hpp

 // SPDX-License-Identifier: MIT
-// Copyright (c) 2018-2023, Advanced Micro Devices, Inc. All rights reserved.
+// Copyright (c) 2023, Advanced Micro Devices, Inc. All rights reserved.
 
 #pragma once