perf stat: Fix cmd_stat to release cpu_map

perf stat: Fix cmd_stat to release cpu_map

Fix cmd_stat() to release cpu_map objects (aggr_map and
cpus_aggr_map) afterwards.

refcnt debugger shows that the cmd_stat initializes cpu_map
but not puts it.
  ----
  # ./perf stat -v ls
  ....
  REFCNT: BUG: Unreclaimed objects found.
  ==== [0] ====
  Unreclaimed cpu_map@0x29339c0
  Refcount +1 => 1 at
    ./perf(cpu_map__empty_new+0x6d) [0x4e64bd]
    ./perf(cmd_stat+0x5fe) [0x43594e]
    ./perf() [0x47b785]
    ./perf(main+0x617) [0x422587]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f2dff420af5]
    ./perf() [0x4226fd]
  REFCNT: Total 1 objects are not reclaimed.
    "cpu_map" leaks 1 objects
  ----

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20151209021127.10245.93697.stgit@localhost.localdomain
[ Remove NULL checks before calling the put operation, it checks it already ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>