Drivers which rely on net80211 to create the beacon need to call
ieee80211_beacon_update() on iv_update_beacon() calls. This is required
that certain bits, e.g. TIM, get updated. A call to ieee80211_beacon_alloc()
is not enough because it does not care about flags which can only change
during runtime. By design a beacon is supposed to be allocated only once
while moving into RUN state.
To handle all possible calls to iv_update_beacon() the run_updateslot()
function has been revived and run_updateprot() has been added.
run_updateslot() handles slot time changes and run_updateprot() changes
to protection, both can change while nodes associate/leave.
Submitted by: Alexander Zagrebin <alex at zagrebin.ru>,
PseudoCylon <moonlightakkiy atyahoo.ca>
MFC after: 3 weeks
e7d14e9bcc