wifi: mac80211: mlme: set sta.mlo to mlo state

At this point, we've already changed link_id to be zero for
a non-MLO connection, so use the 'mlo' variable rather than
link ID to determine the MLO status of the station.

Fixes: bd363ee5 ("wifi: mac80211: mlme: set sta.mlo correctly")
Fixes: 81151ce4 ("wifi: mac80211: support MLO authentication/association with one link")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>