Adding the flag to mac80211 already without testing was
clearly a mistake, one that we now pay for by having to
reserve bit 13 forever. The problem is cfg80211 doesn't
allow capability/rate changes for station entries that
were added unassociated, so the station entries cannot
be set up properly when marked associated.

Change the NL80211_FEATURE_FULL_AP_CLIENT_STATE value
to make it clear to userspace implementations that all
current kernels don't actually support it, even though
the previous bit is set, and of course also remove the
flag from mac80211 until we test and fix the issues.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>