[fix](dfs): fix dfs path max

[PlainWaterK]

[Descriptions]:
1. Current default DFS_PATH_MAX is 4096, but it should be DIRENT_NAME_MAX.

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

The current default DFS_PATH_MAX is 4096, which is not correct

你的解决方案是什么 (what is your solution)

DFS_PATH_MAX should be DIRENT_NAME_MAX

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

• BSP:

• .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

[illustriousness]

lgtm

[BernardXiong]

谢谢提交。不过PATH_MAX似乎和dirent name_max的意思应该不一致才是。dirent name_max指的是一个direntry name的最大值，指的是单个的。而PATH_MAX指的是路径的最大值，应该是多级的关系。

这个问题需要对PATH_MAX做整体引用review后才能看到更清晰的情况。