CVE-2024-57902 af_packet: fix vlan_get_tci() vs MSG_PEEK

In the Linux kernel, the following vulnerability has been resolved: afpacket: fix vlangettci vs MSGPEEK Blamed commit forgot MSGPEEK case, allowing a crash 1 as found by syzbot. Rework vlangettci to not touch skb at all, so that it can be used from many cpus on the same skb. Add a const qualifier...