perf evsel: Fix attr.exclude_kernel setting for default cycles:p

perf evsel: Fix attr.exclude_kernel setting for default cycles:p

To allow probing the max attr.precise_ip setting for non-root users
we unconditionally set attr.exclude_kernel, which makes the detection
work but should be done only for !root, 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: 97365e81366f ("perf evsel: Set attr.exclude_kernel when probing max attr.precise_ip")
Link: http://lkml.kernel.org/n/tip-bl6bbxzxloonzvm4nvt7oqgj@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>