Replace getrandom with arc4random_buf to simplify the usage

[xiaoxiang781216]

Summary

and follow the kernel side change: https://github.com/apache/nuttx/pull/14509

Impact

code refactor only

Testing

ci(need merge https://github.com/apache/nuttx/pull/14509 first)

[nuttxpr]

[Experimental Bot, please feedback here]

No, this PR does not meet the NuttX requirements.

Missing Information:

• Summary:
  • Lacks a clear explanation of the change's purpose (fix, update, new feature).
  • Does not specify the functional part of the code being modified.
  • Provides a vague reference to another PR without detailing the exact changes made in this PR.
• Impact:
  • While stating "code refactor only," it's essential to elaborate on potential ripple effects. For example, were any APIs modified that might impact users?
• Testing:
  • Simply stating "ci" is insufficient. Provide details on:
    • Specific build hosts used (OS, CPU, compiler versions).
    • Target architectures and boards tested.
    • Relevant snippets of testing logs demonstrating the issue before and the improvement after the change.

Recommendations:

1. Expand the Summary: Clearly articulate the PR's purpose, the specific code sections affected, and how this PR differs from the referenced kernel-side change.
2. Thoroughly Address Impact: Even for refactoring, consider potential consequences on users, builds, hardware, documentation, security, and compatibility. If no impact, explicitly state "None."
3. Provide Detailed Testing Information: List the specific build hosts and targets used, and include relevant log excerpts showcasing the problem before the change and the successful outcome after.