CVE-2022-49228 bpf: Fix a btf decl_tag bug when tagging a function

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a btf decltag bug when tagging a function syzbot reported a btf decltag bug with stack trace below: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 1 PREEMPT SMP KASAN KASAN:...