perf top: Ignore kptr_restrict when not sampling the kernel

perf top: Ignore kptr_restrict when not sampling the kernel

If all events have attr.exclude_kernel set, no need to look at
kptr_restrict.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-yegpzg5bf2im69g0tfizqaqz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>