tracing/hwlat: Update old comment about migration

The ftrace hwlat does support a cpumask.

Link: http://lkml.kernel.org/r/20170213122517.6e211955@redhat.com



Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>