If the driver wrapper does not implement passive_scan handler, do not try
to use strerror() to figure out what the error meant. This is not really an
error that the user should be notified about.
(e.g., via driver_nl80211 when using mac80211) instead of using hostapd as
the source of the regulatory information (i.e., information from CRDA is
now used with mac80211); this allows 5 GHz channels to be used with hostapd
(if allowed in the current regulatory domain).
