perf list: Fix --raw-dump option

perf list: Fix --raw-dump option

Currently, 'perf list --raw-dump' requires extra arguments
(e.g., hw) to invoke, which breaks bash/zsh completion
(perf-completion.sh).

  $ perf list --raw-dump
    Error: unknown option `raw-dump'

     usage: perf list [hw|sw|cache|tracepoint|pmu|event_glob]

After,

  $ perf list --raw-dump
  cpu-cycles instructions cache-references cache-misses ...

Signed-off-by: Taesoo Kim <tsgatesv@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Taesoo kim <taesoo@gatech.edu>
Link: http://lkml.kernel.org/r/1419997015-11071-1-git-send-email-tsgatesv@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>