Removed forgotten register_drivers() prototype

Driver registration style was changed long time ago and this is not used
anymore.

hostapd/hostapd.c

@@ -1897,15 +1897,6 @@ fail:
 }
 
 
-/**
- * register_drivers - Register driver interfaces
- *
- * This function is generated by Makefile (into driver_conf.c) to call all
- * configured driver interfaces to register them to core hostapd.
- */
-void register_drivers(void);
-
-
 /**
  * setup_interface_done - Callback when an interface is done being setup.
  * @iface: Pointer to interface data.