Updating error messages for function check_exclude_guest() in perf_event.c

[Treece-Burgess]

Pull Request Description

As stands, if a failure occurs in check_exclude_guest then one of the following errors will output:

Couldn't open hw_instructions in exclude_guest=0 test.
or
Couldn't open hw_instructions in exclude_guest=1 test.

This PR updates both error messages to include:

Set /proc/sys/kernel/perf_event_paranoid to 2 (or less) or run as root.

Such that it indicates to users this is a perf_event_paranoid issue.

Author Checklist

• Description
  Why this PR exists. Reference all relevant information, including background, issues, test failures, etc
• Commits
  Commits are self contained and only do one thing
  Commits have a header of the form: module: short description
  Commits have a body (whenever relevant) containing a detailed description of the addressed problem and its solution
• Tests
  The PR needs to pass all the tests