perf evsel: Do not call pevent_free_format when deleting tracepoint

perf evsel: Do not call pevent_free_format when deleting tracepoint

The libtraceevent library's main handle 'struct pevent' holds pointers
of every event that was added to it via functions:

  pevent_parse_format
  pevent_parse_event

We can't release struct event_format (call pevent_free_format)
separately, because that breaks that pointers array mentioned above and
another add_event call could end up with segfault.

All added events are released within the handle cleanup in pevent_free.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1415098538-1512-1-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>