tools, bpftool: Fix wrong return value in do_dump()

In case of btf_id does not exist, a negative error code -ENOENT
should be returned.

Fixes: c93cc69 ("bpftool: add ability to dump BTF types")
Signed-off-by: Tianjia Zhang <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Reviewed-by: Tobias Klauser <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Acked-by: John Fastabend <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: uudiin

tools/bpf/bpftool/btf.c

@@ -596,7 +596,7 @@ static int do_dump(int argc, char **argv)
 			goto done;
 		}
 		if (!btf) {
-			err = ENOENT;
+			err = -ENOENT;
 			p_err("can't find btf with ID (%u)", btf_id);
 			goto done;
 		}