mac80211: don't advertise NL80211_FEATURE_FULL_AP_CLIENT_STATE

For now, this feature doesn't actually work. To avoid shipping a
kernel that has it enabled but where it can't be used disable it
for now - we can re-enable it when it's fixed.

This partially reverts 44674d9c ("mac80211: advertise support
for full station state in AP mode").

Cc: Ayala Beker <ayala.beker@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>