Allow WPS APs for PIN enrollment even without Selected Registrar

Allow WPS APs for PIN enrollment even without Selected Registrar

Some WPS APs do not set Selected Registrar attribute to 1 properly when
using an external Registrar. Allow such an AP to be selected for PIN
registration after couple of scan runs that do not find APs marked with
Selected Registrar = 1. This allows wpa_supplicant to iterate through
all APs that advertise WPS support without delaying connection with
implementations that set Selected Registrar = 1 properly.