fs: remove unneeded return statement

The `writable._write()` implementation does not need to return anything,
only call the callback.

PR-URL: #48526
Reviewed-By: Keyhan Vakil <kvakil@sylph.kvakil.me>
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>
Reviewed-By: Deokjin Kim <deokjin81.kim@gmail.com>

Author: lpinca

lib/internal/fs/sync_write_stream.js

@@ -25,7 +25,6 @@ ObjectSetPrototypeOf(SyncWriteStream, Writable);
 SyncWriteStream.prototype._write = function(chunk, encoding, cb) {
   writeSync(this.fd, chunk, 0, chunk.length);
   cb();
-  return true;
 };
 
 SyncWriteStream.prototype._destroy = function(err, cb) {

test/parallel/test-internal-fs-syncwritestream.js

@@ -36,7 +36,12 @@ const filename = path.join(tmpdir.path, 'sync-write-stream.txt');
   const stream = new SyncWriteStream(fd);
   const chunk = Buffer.from('foo');
 
-  assert.strictEqual(stream._write(chunk, null, common.mustCall(1)), true);
+  let calledSynchronously = false;
+  stream._write(chunk, null, common.mustCall(() => {
+    calledSynchronously = true;
+  }, 1));
+
+  assert.ok(calledSynchronously);
   assert.strictEqual(fs.readFileSync(filename).equals(chunk), true);
 
   fs.closeSync(fd);