test: update test/parallel/test-fs-read.js

* Replace equal with strictEqual
* Update functions to arrow functions

PR-URL: https://github.com/nodejs/node/pull/8596


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>