test: refactor test-fs-read-zero-length.js

PR-URL: https://github.com/nodejs/node/pull/10729
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-fs-read-zero-length.js

@@ -7,7 +7,7 @@ const filepath = path.join(common.fixturesDir, 'x.txt');
 const fd = fs.openSync(filepath, 'r');
 const expected = '';
 
-fs.read(fd, 0, 0, 'utf-8', common.mustCall(function(err, str, bytesRead) {
+fs.read(fd, 0, 0, 'utf-8', common.mustCall((err, str, bytesRead) => {
   assert.ok(!err);
   assert.strictEqual(str, expected);
   assert.strictEqual(bytesRead, 0);