Extend hostapd to allow the new OSU Provider NAI List ANQP-element to be
advertised in addition to the previously used OSU Providers list
ANQP-element. The new osu_nai2 configurator parameter option is used to
specify the OSU_NAI value for the shared BSS (Single SSID) case while
osu_nai remains to be used for the separate OSU BSS.