firmware: Disable the Nagle algorithm on sockets

[mbirtwell]

ARTIQ Pull Request

Description of Changes

Disable the nagle algorithm to fix #2601

The experiment on #2601 goes from about 50ms per RPC to 2.7ms per RPC for me.

Related Issue

Type of Changes

	Type
✓	:bug: Bug fix

Steps (Choose relevant, delete irrelevant before submitting)

All Pull Requests

• [x] Use correct spelling and grammar.
• [ ] Update RELEASE_NOTES.rst if there are noteworthy changes, especially if there are changes to existing APIs.
• [x] Close/update issues.
• [x] Check the copyright situation of your changes and sign off your patches (git commit --signoff, see copyright).

Documentation Changes

• [ ] Check, test, and update the documentation in doc/. Build documentation (nix build .#artiq-manual-html; nix build .#artiq-manual-pdf) to ensure no errors.

Git Logistics

• [x] Split your contribution into logically separate changes (git rebase --interactive). Merge/squash/fixup commits that just fix or amend previous commits. Remove unintended changes & cleanup. See tutorial.

• [x] Write short & meaningful commit messages. Review each commit for messages (git show). Format:

  topic: description. < 50 characters total.
  
  Longer description. < 70 characters per line

Licensing

See copyright & licensing for more info. ARTIQ files that do not contain a license header are copyrighted by M-Labs Limited and are licensed under LGPLv3+.

[thomasfire]

I checked the patch, works fine. Thanks!

[dnadlinger]

Merged, thanks (having added firmware: to the commit message to make it clear at a glance that this is on the core-device side).