crypto: remove default encoding from pbkdf2

Refs: #47182
PR-URL: #47869
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/internal/crypto/pbkdf2.js

@@ -20,7 +20,6 @@ const {
 
 const {
   getArrayBufferOrView,
-  getDefaultEncoding,
   normalizeHashName,
   kKeyObject,
 } = require('internal/crypto/util');
@@ -49,14 +48,11 @@ function pbkdf2(password, salt, iterations, keylen, digest, callback) {
     keylen,
     digest);
 
-  const encoding = getDefaultEncoding();
   job.ondone = (err, result) => {
     if (err !== undefined)
       return FunctionPrototypeCall(callback, job, err);
     const buf = Buffer.from(result);
-    if (encoding === 'buffer')
-      return FunctionPrototypeCall(callback, job, null, buf);
-    FunctionPrototypeCall(callback, job, null, buf.toString(encoding));
+    return FunctionPrototypeCall(callback, job, null, buf);
   };
 
   job.run();
@@ -78,9 +74,7 @@ function pbkdf2Sync(password, salt, iterations, keylen, digest) {
   if (err !== undefined)
     throw err;
 
-  const buf = Buffer.from(result);
-  const encoding = getDefaultEncoding();
-  return encoding === 'buffer' ? buf : buf.toString(encoding);
+  return Buffer.from(result);
 }
 
 function check(password, salt, iterations, keylen, digest) {