Update on "[Execuotrch][cpuinfo] Add util to find out # of performant cores"

This helps with identifying the # of performant cores which will later be used
when reseting the threadpool or using the guard to figure out how many threads
should be used

Differential Revision: [D54766068](https://our.internmc.facebook.com/intern/diff/D54766068/)

[ghstack-poisoned]

Author: kimishpatel

backends/xnnpack/threadpool/cpuinfo_utils.cpp

@@ -8,7 +8,6 @@
 
 #include <executorch/runtime/platform/assert.h>
 #include <fstream>
-#include <iostream>
 #include <mutex>
 #include <string>
 #include <vector>