Remove duplicate in bpf_skb_change_tail definition

[ippishio]

No description provided.

[dylandreimerink]

I think this should have been bpf_l4_csum_replace, and forgot to update it after copy-paste.

Suggested change

The basic idea is that the helper performs the needed work to change the size of the packet, then the eBPF program rewrites the rest via helpers like **bpf_skb_store_bytes**(), **bpf_l3_csum_replace**(), **bpf_l3_csum_replace**() and others. This helper is a slow path utility intended for replies with control messages. And because it is targeted for slow path, the helper itself can afford to be slow: it implicitly linearizes, unclones and drops offloads from the _skb_.

The basic idea is that the helper performs the needed work to change the size of the packet, then the eBPF program rewrites the rest via helpers like **bpf_skb_store_bytes**(), **bpf_l3_csum_replace**(), **bpf_l4_csum_replace**() and others. This helper is a slow path utility intended for replies with control messages. And because it is targeted for slow path, the helper itself can afford to be slow: it implicitly linearizes, unclones and drops offloads from the _skb_.