LinuxKPI: 802.11: further improve key updates

Make sure the iv_bss noce does not go away in the middle of a key update
given we unlocked. Just as a precaution. No real case has been seen
so far.

Sponsored by: The FreeBSD Foundation
Fixes: a6165709e3c8

(cherry picked from commit a6413bce4e36e4176bbcf16528cc3aeb834965ba)