Plane: update AP_Notify flags for arming state

ArduPlane/ArduPlane.pde

@@ -966,6 +966,10 @@ static void one_second_loop()
     mavlink_system.sysid = g.sysid_this_mav;
 
     update_aux();
+
+    // update notify flags
+    AP_Notify::flags.pre_arm_check = arming.pre_arm_checks(false);
+    AP_Notify::flags.armed = arming.is_armed() || arming.arming_required() == AP_Arming::NO;
 }
 
 static void log_perf_info()