[libcpu][risc-v] 减少rv64 smart版本中mmu early map时的地址空间大小以防止cpu猜测执行到不存在的地址空间

[zhangjing0303]

…egment is located

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

rv64 smart版本中，在rt_hw_mem_setup_early中会开启MMU大页映射（1GB）,映射地址范围从0-512G，远超出实际板卡的内存地址空间，板卡上运行时，会出现cpu随机猜测执行到某段不存在的物理地址，导致CPU发生NMI异常。

你的解决方案是什么 (what is your solution)

根据实际需要，只映射代码段所在的1个大页。

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

• BSP: bsp/qemu-virt64-riscv

• .config:

• action:

]

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/workflows/bsp_buildings.yml 详细请参考链接BSP自查

[supperthomas]

请添加yml，让CI编译检查可以检查到，参考qemu-vexpress-a9的smart配置

[Copilot]

Pull Request Overview

This pull request reduces the MMU early mapping area in the rv64 smart version, limiting the mapping to only the code segment's large page.

• Replaces a for‑loop mapping multiple pages with a single mapping based on the aligned code address.
• Ensures that only the necessary address space is mapped to prevent CPU speculation to unmapped memory.

[Rbb666]

请添加yml，让CI编译检查可以检查到，参考qemu-vexpress-a9的smart配置

涛哥，我看了下这个CI是会build到这个文件的：
https://github.com/RT-Thread/rt-thread/actions/runs/15296831355/job/43027800393?pr=10332