LinuxKPI: 802.11: update the ni/lsta reference cycle

Update the ni/lsta reference cycle, add extra checks and assertions.
This is to accomodate problems we were seeing based on net80211
behaviour (join1() and (*iv_update_bss)() as well as state changes for
new iv_bss nodes during an active session).
This should hopefully help to stabilise behaviour until the underlying
problems gets properly addressed (for this and all other device drivers).

Approved by: re (cperciva)
PR: 272607, 273985, 274003
Reviewed by: cc
Differential Revision: https://reviews.freebsd.org/D43753

(cherry picked from commit 0936c648ad0ee5152dc19f261e77fe9c1833fe05)
(cherry picked from commit 223edc1a3c2fc86dbc7fa0ecd00f26a85d7c7b43)