perf tools: Fix assertion failure on dynamic entry

The dynamic entry is created for each field in a tracepoint event.
Since they have no fixed hpp format index, it should skip when
perf_hpp__reset_width() is called.

This caused following assertion failure..

  $ perf record -e sched:sched_switch -a sleep 1

  $ perf report -s comm,next_pid --stdio
  perf: ui/hist.c:651: perf_hpp__reset_width:
    Assertion `!(fmt->idx >= PERF_HPP__MAX_INDEX)' failed.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1456064558-13086-1-git-send-email-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>