LinuxKPI: 802.11: extend ieee80211_key_seq and WLAN_KEY_LEN_* defines

For iwlwifi(4) d3.c we need another struct in struct ieee80211_key_seq
and related WLAN_KEY_LEN_* defines in.

Reviewed by: cc, emaste
Differential Revision: https://reviews.freebsd.org/D43646

(cherry picked from commit 2f029bf911e29dc46c32ea142daba4f26a2078f4)