mac80211_hwsim: indicate in IBSS that we have transmitted beacons

This is actually true because there's no functional beacon distribution
and lets us get active scanning working - without it, mac80211 doesn't
respond to probe requests.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200326150855.554d1199b309.Id86fd36e3d88d2a75d6e0c6618fd93ce8fe84065@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>