mac80211: combine QoS with other BSS changes

When associating and particularly when disassociating
there's no need to notify the driver about changes
with multiple calls to bss_info_changed, we should
combine the QoS enabling/disabling into the same call
as otherwise the driver could get confused about QoS
suddenly getting disabled while connected.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>