mac80211_hwsim: enable TODS BIT in null data frame

Same as in ieee80211_nullfunc_get, enable the TODS bit, otherwise the
nullfunc packet will not be handled in ap rx path.
(will be dropped in ieee80211_accept_frame()).

Signed-off-by: Adiel Aloni <adiel.aloni@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>