Replace driver wrapper calls to hostapd_tx_status(),
hostapd_rx_from_unknown_sta(), hostapd_mgmt_rx(), and
hostapd_mgmt_tx_cb() with new generic driver events
EVENT_TX_STATUS, EVENT_RX_FROM_UNKNOWN, and EVENT_RX_MGMT.
This cleans up lot of the driver wrapper code to be less dependent
on whether it is being used within wpa_supplicant AP mode or hostapd.
When in AP mode, wpa_supplicant is now enabling WPS (only Internal
Registrar). wpa_cli wps_pbc and wps_pin commands can be used to initiate
WPS negotiation similarly to how this is done in station mode (though,
the BSSID parameter is ignored).
wpa_supplicant can now initialize hostapd data structures when mode=2 is
used to set up an AP. The hostapd configuration is not yet set based on
wpa_supplicant network configuration block. In addition, the glue code
for hostapd driver_ops needs number of functions that will be needed for
AP functionality.
