fs: remove unused parameter for encodeRealpathResult

The third parameter `err` is not used anywhere.

PR-URL: nodejs#10862
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/fs.js

@@ -1453,8 +1453,8 @@ const splitRootRe = isWindows ?
   /^(?:[a-zA-Z]:|[\\/]{2}[^\\/]+[\\/][^\\/]+)?[\\/]*/ :
   /^[/]*/;
 
-function encodeRealpathResult(result, options, err) {
-  if (!options || !options.encoding || options.encoding === 'utf8' || err)
+function encodeRealpathResult(result, options) {
+  if (!options || !options.encoding || options.encoding === 'utf8')
     return result;
   const asBuffer = Buffer.from(result);
   if (options.encoding === 'buffer') {