[gd32][uart] Add GD32VW553 series UART driver support

[zhang-haitao-repo]

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

• 1. 解决GD32VW553 menuconfig配置UART1/2之后，会编译报错找不到USART1/2的问题；
• 2. 解决GD32VW553 执行menuconfig配置会出现实际硬件上不存在的UART3/4配置项的问题；
• 3. 修复由于当前写死端口复用功能,导致gpio无法完整映射到UART1/2；
• 4. 修复由于中断名称错误，导致的GD32VW553 Uart1/2中断向量表未正确映射的问题；

你的解决方案是什么 (what is your solution)

• 1. 在uart_drv.c中增加针对GD32VW553 Uart模块的支持；
• 2. 删除GD32VW553中不存在的Uart3/4；
• 3. 在drv_uart.c/h中增加针对GD32VW553的端口复用配置；
• 4. 同第一条；

请提供验证的bsp和config (provide the config and bsp)

• BSP: bsp/gd32/risc-v/gd32vw553h-eval

• .config: none

• action: none

]

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
• 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:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 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
• 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
• 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
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 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
• 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

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[github-actions]

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完成后，提交将自动更新至 feat/gd32vw55x-usart-support 分支，关联的 Pull Request 也会同步更新。
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[Copilot]

Pull request overview

This PR adds UART driver support for the GD32VW553 series microcontroller by implementing SOC-specific differentiation between GD32VF103V and GD32VW55x families within the existing GD32 RISC-V BSP framework.

Changes:

• Adds conditional GPIO alternate function configuration support for GD32VW55x UART peripherals
• Implements correct interrupt vector naming (UART1/2 vs USART1/2) for GD32VW55x series
• Removes non-existent UART3/4 configuration options from GD32VW553H Kconfig

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
bsp/gd32/risc-v/libraries/gd32_drivers/drv_usart.h	Adds tx_alt and rx_alt fields to gd32_uart struct for GD32VW55x GPIO alternate function configuration
bsp/gd32/risc-v/libraries/gd32_drivers/drv_usart.c	Implements SOC-specific interrupt handlers, UART peripheral definitions, and GPIO initialization with alternate function support for GD32VW55x
bsp/gd32/risc-v/gd32vw553h-eval/board/Kconfig	Removes UART3/4 configuration options that don't exist in GD32VW553H hardware