perf hists browser: Fix callchain print bug on TUI

Currently perf report -g graph option doesn't work as expected and
always work as same as -g fractal.  This was a bug during recent
callchain print code cleanup.

Before:
  $ perf report -g graph

    Children      Self  Command  Shared Object      Symbol
  ================================================================
  -   56.19%    35.41%  sleep    [kernel.kallsyms]  [k] page_fault
     - page_fault
        + 63.02% _dl_relocate_object
        + 36.98% clear_user

After:
    Children      Self  Command  Shared Object      Symbol
  ================================================================
  -   56.19%    35.41%  sleep    [kernel.kallsyms]  [k] page_fault
     - page_fault
        + 35.41% _dl_relocate_object
        + 20.78% clear_user

Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Milian Wolff <mail@milianw.de>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1411434104-5307-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>