readline: remove unneeded eslint-disable comment

Remove a comment disabling an ESLint rule that is not triggered by the
code anyway.

PR-URL: https://github.com/nodejs/node/pull/11836


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>