mac80211: Implement add_nan_func and rm_nan_func

Implement add/rm_nan_func functions and handle NAN function
termination notifications. Handle instance_id allocation for
NAN functions and implement the reconfig flow.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>