perf hists: Return correct number of characters printed in callchain

Include the omitted number of characters printed for the first entry.

Not that it really matters because nobody seem to care about the number
of printed characters for now. But just in case.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1342631456-7233-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>