[Bug] frequency penalty

[vivian0429]

Checklist

• [ ] 1. I have searched related issues but cannot get the expected help.
• [ ] 2. The bug has not been fixed in the latest version.
• [ ] 3. Please note that if the bug-related issue you submitted lacks corresponding environment info and a minimal reproducible demo, it will be challenging for us to reproduce and resolve the issue, reducing the likelihood of receiving feedback.
• [ ] 4. If the issue you raised is not a bug but a question, please raise a discussion at https://github.com/sgl-project/sglang/discussions/new/choose Otherwise, it will be closed.
• [ ] 5. Please use English, otherwise it will be closed.

Describe the bug

It seems there are some issue in the frequency_penalty implementation.

Reproduction

code issue

Environment

skip

[merrymercy]

please help us fix it