resctrl_tests can be built or run using kselftests framework.
Add description on how to do so in README.
Reviewed-by: NReinette Chatre <reinette.chatre@intel.com>
Reviewed-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NShaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Signed-off-by: NShuah Khan <skhan@linuxfoundation.org>