buffer: remove unnecessary assignment in fromString

The assignment to the encoding variable has no effect.

Refs: #29217
PR-URL: #50199
Reviewed-By: Yagiz Nizipli <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: tniessen

lib/buffer.js

@@ -475,7 +475,6 @@ function fromString(string, encoding) {
     if (string.length === 0)
       return new FastBuffer();
     ops = encodingOps.utf8;
-    encoding = undefined;
   } else {
     ops = getEncodingOps(encoding);
     if (ops === undefined)