tracing: Fix comments for event_trigger_separate_filter()

The parameter name in comments of event_trigger_separate_filter() is
inconsistent with actual parameter name, fix it.

Link: https://lkml.kernel.org/r/20220526072957.165655-1-sunliming@kylinos.cn



Signed-off-by: sunliming <sunliming@kylinos.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>