We should set attr.exclude_kernel when probing for attr.precise_ip
level, otherwise !CAP_SYS_ADMIN users will not default to skidless
samples in capable hardware.

The increase in the paranoid level in commit 0161028b ("perf/core:
Change the default paranoia level to 2") broke this, fix it by excluding
kernel samples when probing.

Before:

  $ perf record usleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.018 MB perf.data (6 samples) ]
  $ perf evlist -v
  cycles:u: sample_freq: 4000, sample_type: IP|TID|TIME|PERIOD, exclude_kernel: 1

After:

  $ perf record usleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.018 MB perf.data (8 samples) ]
  $ perf evlist -v
  cycles:ppp: sample_freq: 4000, sample_type: IP|TID|TIME|PERIOD, exclude_kernel: 1, precise_ip: 3
                                                                                     ^^^^^^^^^^^^^
                                                                                     ^^^^^^^^^^^^^
                                                                                     ^^^^^^^^^^^^^
  $

To further clarify: we always set .exclude_kernel when non !CAP_SYS_ADMIN
users profile, its just on the attr.precise_ip probing that we weren't doing
so, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 7f8d1ade ("perf tools: By default use the most precise "cycles" hw counter available")
Link: http://lkml.kernel.org/n/tip-t2qttwhbnua62o5gt75cueml@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>