perf tools: Make perf_evsel__(nr_)cpus generic

perf tools: Make perf_evsel__(nr_)cpus generic

Because we now propagate all evlist's cpu_maps and thread_map objects
through all evsels, the perf_evsel__(nr_)cpus no longer need to be
specific to stat object and check evlist and target objects.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1435012588-9007-8-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>