scripts/tags.sh: Add magic for trace-events for etags too

Seems that Peter Zijlstra treats us emacs users as second class
citizens and the commit:

 commit 15664125
 Author: Peter Zijlstra <peterz@infradead.org>
 scripts/tags.sh: Add magic for trace-events

only updated ctags (for vim) and did not do the work to let us
lowly emacs users benefit from such a change.

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>