[timer][core]定时器回调临时保持后在触发回调

[yuqingli05]

拉取/合并请求描述：(PR description)

[ 问题：定时器回调因为在锁外部执行，有可能被其他高优先级中断或线程修改回调变量的风险 解决办法：定义临时变量保存回调函数和回调参数 ]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• [ ] 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• [x] 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• [x] 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• [x] 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• [x] 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• [x] 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• [x] 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• [x] 代码是高质量的 Code in this PR is of high quality
• [ ] 已经使用formatting 等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification