fs: remove no-longer-relevant comment

The comment suggests that the subsequent code could by DRYed up, due to
simply passing arguments along. However, in the commits since then, this
no longer appears to apply, and so the comment is now confusing with
respect to the current code.

PR-URL: https://github.com/nodejs/node/pull/16285


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>