ArduSub: remove comment for already-removed in-delay-callback function

These are now attached to completely unrelated functions, which is
pretty bad.

ArduSub/GCS_Mavlink.cpp

@@ -788,13 +788,6 @@ void GCS_MAVLINK_Sub::handle_rc_channels_override(const mavlink_message_t &msg)
     GCS_MAVLINK::handle_rc_channels_override(msg);
 }
 
-
-/*
- *  a delay() callback that processes MAVLink packets. We set this as the
- *  callback in long running library initialisation routines to allow
- *  MAVLink to process packets while waiting for the initialisation to
- *  complete
- */
 MAV_RESULT GCS_MAVLINK_Sub::handle_flight_termination(const mavlink_command_long_t &packet) {
     if (packet.param1 > 0.5f) {
         sub.arming.disarm(AP_Arming::Method::TERMINATION);