CVE-2022-48929 bpf: Fix crash due to out of bounds access into reg2btf_ids.

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix crash due to out of bounds access into reg2btfids. When commit e6ac2450d6de "bpf: Support bpf program calling kernel function" added kfunc support, it defined reg2btfids as a cheap way to translate the verifier reg type ...