Add some bsp driver for HC32F4A8.

[JamieTx]

拉取/合并请求描述：(PR description)

[ Add some bsp driver for HC32F4A8. ]

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
• [x] 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
• [x] 如果是新增bsp, 已经添加ci检查到.github/workflows/bsp_buildings.yml 详细请参考链接BSP自查

[JamieTx]

Pull Request Overview

This PR adds support and driver updates for the HC32F4A8 MCU variant, extending existing HAL layers and board configurations.

• Enable HC32F4A8 in RTC, PM, MCAN, ETH, and DAC drivers
• Introduce VBAT power-down check for RTC initialization
• Update board-specific ports, Kconfig entries, and application code for F4A8

Reviewed Changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 3 comments.

Show a summary per file Comments suppressed due to low confidence (2)

这个PR还有什么问题要处理吗？没有看到新的异常

[JamieTx]

Pull Request Overview

This PR adds support and driver updates for the HC32F4A8 MCU variant, extending existing HAL layers and board configurations.

• Enable HC32F4A8 in RTC, PM, MCAN, ETH, and DAC drivers
• Introduce VBAT power-down check for RTC initialization
• Update board-specific ports, Kconfig entries, and application code for F4A8

Reviewed Changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 3 comments. Show a summary per file Comments suppressed due to low confidence (2)

这个PR还有什么问题要处理吗？没有看到新的异常 @supperthomas

[supperthomas]

请针对某一款常用的bsp，添加对应yml文件，方便其他人知道如何使用这些driver

添加yml参考如下：

https://club.rt-thread.org/ask/article/5c41835bb8ff9b41.html

https://club.rt-thread.org/ask/article/d273bbcd1f8779bc.html

[Rbb666]

@JamieTx 作者是否有意愿维护此BSP,可以申请加入审核团：https://github.com/RT-Thread/rt-thread/blob/master/MAINTAINERS