fs: replace a bind() with a top-level function

https://github.com/nodejs/node/pull/11225 introduce an unnecessary
bind() when closing a stream. This PR replaces that bind() with a
top-level function.

PR-URL: https://github.com/nodejs/node/pull/13474


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Evan Lucas <evanlucas@me.com>