PerfKvmCounter::attach recieved error EACCESS

```
This error may be caused by a too restrictive setting
  in the file '/proc/sys/kernel/perf_event_paranoid'
  The default value was changed to 2 in kernel 4.6
  A value greater than 1 prevents gem5 from making
  the syscall to perf_event_open
```

This can be fixed by running one of the following commands:
```
sudo sysctl -w kernel.perf_event_paranoid=1
make fix_perf
```