Add scheduled scan driver operations

In new Linux kernel versions (>=3.0), nl80211 adds scheduled scan
capability. In order to use this feature to its full extent, we need
to support it in the wpa_supplicant core, so that it can also be used
by other drivers.

This commit adds initial scheduled scan support operations and events.

Signed-off-by: Luciano Coelho <coelho@ti.com>

src/drivers/driver_ndis.c

@@ -3331,5 +3331,7 @@ const struct wpa_driver_ops wpa_driver_ndis_ops = {
 	NULL /* sta_assoc */,
 	NULL /* sta_auth */,
 	NULL /* add_tspec */,
-	NULL /* add_sta_node */
+	NULL /* add_sta_node */,
+	NULL /* sched_scan */,
+	NULL /* stop_sched_scan */
 };