scripts/tags.sh: Fix ctags for DEFINE_EVENT()

The regex to handle DEFINE_EVENT() should not be the same as
the TRACE_EVENT() as the first parameter in DEFINE_EVENT is the
template name, not the event name. We need the second parameter
as that is what the trace_... will use.

Tested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>