[bsp][k230] add K230D support and Smart improvements

[BernardXiong]

拉取/合并请求描述：(PR description)

为什么提交这份PR (why to submit this PR)

The K230 BSP only targeted the 512MB K230 board and had no K230D (128MB DDR)
variant. It also lacked a pin device, ext4 rootfs support and pseudo terminal
mount points required by the Smart configuration.

你的解决方案是什么 (what is your solution)

• add SOC_K230/SOC_K230D selection and size the default memory layout for 128MB DDR
• register GPIO as an RT-Thread pin device
• add ext4 rootfs support and mount ptyfs and procfs
• remove unused board peripheral definitions
• keep the SDK riscv64-unknown-linux-musl toolchain and lp64d ABI
• regenerate .config and rtconfig.h

Dependencies

• Depends on [libcpu][riscv] fix MMU and user fault handling for Smart #11892 (ARCH_RISCV_XUANTIE, SVPBMT and RISC-V MMU fixes)
• Depends on [net][lwip] add loopback netdev support #11893 (RT_LWIP_USING_LOOPBACK Kconfig symbol)
• Recommended together with [drivers][serial] improve TIOCGWINSZ and termios updates #11891 (serial TIOCGWINSZ handling)
• Requires the lwext4 package from the package index
• The .config and rtconfig.h files were generated with [libcpu][riscv] fix MMU and user fault handling for Smart #11892 and [net][lwip] add loopback netdev support #11893
  applied. This PR will be rebased and the configuration regenerated after
  the dependencies are merged.

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

• BSP: bsp/k230 (K230D, 128MB DDR)
• .config: CONFIG_SOC_K230D=y, CONFIG_BSP_ROOTFS_TYPE_EXT4=y, CONFIG_BSP_USING_GPIO=y, CONFIG_RT_USING_PIN=y
• action: built locally with the K230 SDK riscv64-unknown-linux-musl toolchain; CI will verify the configuration

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clang-format 源码格式化工具确保格式符合RT-Thread代码规范 This PR has been formatted with clang-format and 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

[github-actions]

MemBrowse Memory Report

k230

• SRAM: .bss +61,536 B, .data +1,088 B, .eh_frame +24,104 B, .sbss +120 B, .srodata.cst8 +32 B, .text +117,856 B (+18.1%, 1,333,275 B / 60,682,240 B, total: 2% used)