fix: update bbdev for process tree cleanup

[daiyongyuan]

Summary

• Advance the bbdev submodule to the process-tree cleanup fix in fix: terminate detached descendants on bbdev cancellation bbdev#20.
• This makes interrupted P2E workloads clean up detached descendants before a later FPGA flash.

Dependency

• Merge fix: terminate detached descendants on bbdev cancellation bbdev#20 first so the referenced submodule commit is available on bbdev main.

Validation

• The bbdev cleanup tests passed (2 tests).
• Both branches are based on their repositories' latest remote main.