perf report: Ignore kptr_restrict when not sampling the kernel

perf report: Ignore kptr_restrict when not sampling the kernel

If none of the evsels has attr.exclude_kernel set to zero, no kernel
samples, so no point in warning the user about problems in processing
kernel samples, as there will be none.

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-7dn926v3at8txxkky92aesz2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>