bpf: Fix a typo "inacitve" -> "inactive"

There is a typo in struct bpf_lru_list's next_inactive_rotation
description, thus fix s/inacitve/inactive/.

Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1585901254-30377-1-git-send-email-hqjagain@gmail.com