bpf: Protect probed address based on kptr_restrict setting

The probed address can be accessed by userspace through querying the task
file descriptor (fd). However, it is crucial to adhere to the kptr_restrict
setting and refrain from exposing the address if it is not permitted.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-5-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>