modules: CMSIS_6: update copyright

As noted in PR #89370, the content of these files falls below the
trivial threshold. Therefore, it is not necessary to retain the original
copyright, which was carried over when the files were copied from the
`cmsis` module.

Signed-off-by: Sudan Landge <sudan.landge@arm.com>

modules/cmsis_6/CMakeLists.txt

@@ -1,4 +1,3 @@
-# Copyright (c) 2023 Nordic Semiconductor ASA
 # Copyright 2025 Arm Limited and/or its affiliates <open-source-office@arm.com>
 # SPDX-License-Identifier: Apache-2.0
 

modules/cmsis_6/cmsis_core.h

@@ -1,5 +1,4 @@
 /*
- * Copyright (c) 2023 Nordic Semiconductor ASA
  * Copyright 2025 Arm Limited and/or its affiliates <open-source-office@arm.com>
  * SPDX-License-Identifier: Apache-2.0
  */