Use simplify self assignment syntax fix ci error

[Jzow]

Description

Related Issue: CI Job 19631287750 and CI Job 19630769043

Pre-commit steps

• Tested on QEMU and real HW Rasperry Pi.
  • Not needed if it is just a README change or similar.
• Ran ./contributor_setup.sh followed by ./devtool ready_for_publish
  • You'll need Ruby with Bundler and NPM installed locally.
  • If no Rust-related files were changed, ./devtool ready_for_publish_no_rust can be used instead (faster).
  • This step is optional, but much appreciated if done.

[eldruin]

Thank you for fixing this!