With bpf_get_probe_write_proto() no longer printing a message, we can
avoid it being a special case with its own permission check.
Refactor bpf_tracing_func_proto() similar to bpf_base_func_proto() to
have a section conditional on bpf_token_capable(CAP_SYS_ADMIN), where
the proto for bpf_probe_write_user() is returned. Finally, remove the
unnecessary bpf_get_probe_write_proto().
This simplifies the code, and adding additional CAP_SYS_ADMIN-only
helpers in future avoids duplicating the same CAP_SYS_ADMIN check.
Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>