[Kernel] Adjust the copyright information

libcpu/arm/cortex-m4/context_rvds.S

@@ -1,12 +1,8 @@
 ;/*
-; * File      : context_rvds.S
-; * This file is part of RT-Thread RTOS
-; * COPYRIGHT (C) 2006 - 2018, RT-Thread Development Team
-; *
-; * The license and distribution terms for this file may be
-; * found in the file LICENSE in this distribution or at
-; * http://www.rt-thread.org/license/LICENSE
-; *
+;* Copyright (c) 2006-2018, RT-Thread Development Team
+;*
+;* SPDX-License-Identifier: Apache-2.0
+;*
 ; * Change Logs:
 ; * Date           Author       Notes
 ; * 2009-01-17     Bernard      first version.