LinuxKPI: 802.11: more fields moved from vif to bss_conf

csa_active, color_change_active, mu_mimo_owner also moved from
vif to bss_conf; we already have the fields in bss_conf (adjust type
for one) so all we have to do is remove the old relics in vif.

Sponsored by: The FreeBSD Foundation
Tested by: Oleksandr Kryvulia (shuriku shurik.kiev.ua)
Tested by: Oleg Nauman (oleg.nauman gmail.com) [rtw88]
Differential Revision: https://reviews.freebsd.org/D49734

(cherry picked from commit 5321cf2b15d7bff1b01182cfc4897ac978c63fe7)