stream: remove useless initializiation of stream.fd

lib/internal/fs/streams.js

@@ -175,7 +175,6 @@ function ReadStream(path, options) {
 
   // Path will be ignored when fd is specified, so it can be falsy
   this.path = toPathIfFileURL(path);
-  this.fd = options.fd === undefined ? null : options.fd;
   this.flags = options.flags === undefined ? 'r' : options.flags;
   this.mode = options.mode === undefined ? 0o666 : options.mode;