feat: add command to enable mptcp (backport #4014)

[mergify]

Overview

adds a makefile command to enable and disable mptcp over different ports (not interfaces) for linux kernels greater than 5.6

not required, but potentially useful

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This is an automatic backport of pull request #4014 done by Mergify.

[mergify]

Cherry-pick of 808d0f2 has failed:

On branch mergify/bp/v2.x/pr-4014
Your branch is up to date with 'origin/v2.x'.

You are currently cherry-picking commit 808d0f21.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   Makefile

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[evan-forbes]

we don't really have to merge this

[evan-forbes]

not worth fixing the conflict tbh