GCS_MAVLink: move orderly rebooting code from GCS into AP_Vehicle

Several places we reboot the vehicle we should probably do several of
the things done in this code - flushing parameters, forcing safety on
etc.

libraries/GCS_MAVLink/GCS.h

@@ -416,7 +416,6 @@ protected:
     void handle_common_message(const mavlink_message_t &msg);
     void handle_set_gps_global_origin(const mavlink_message_t &msg);
     void handle_setup_signing(const mavlink_message_t &msg);
-    virtual bool should_zero_rc_outputs_on_reboot() const { return false; }
     virtual MAV_RESULT handle_preflight_reboot(const mavlink_command_long_t &packet);
 
     // reset a message interval via mavlink:

libraries/GCS_MAVLink/GCS_Common.cpp

@@ -2656,34 +2656,13 @@ MAV_RESULT GCS_MAVLINK::handle_preflight_reboot(const mavlink_command_long_t &pa
         return MAV_RESULT_UNSUPPORTED;
     }
 
-    if (should_zero_rc_outputs_on_reboot()) {
-        SRV_Channels::zero_rc_outputs();
-    }
-
     // send ack before we reboot
     mavlink_msg_command_ack_send(chan, packet.command, MAV_RESULT_ACCEPTED);
-    // Notify might want to blink some LEDs:
-    AP_Notify *notify = AP_Notify::get_singleton();
-    if (notify) {
-        AP_Notify::flags.firmware_update = 1;
-        notify->update();
-    }
-    // force safety on
-    hal.rcout->force_safety_on();
-
-    // flush pending parameter writes
-    AP_Param::flush();
-
-    // do not process incoming mavlink messages while we delay:
-    hal.scheduler->register_delay_callback(nullptr, 5);
-
-    // delay to give the ACK a chance to get out, the LEDs to flash,
-    // the IO board safety to be forced on, the parameters to flush, ...
-    hal.scheduler->delay(200);
 
     // when packet.param1 == 3 we reboot to hold in bootloader
     const bool hold_in_bootloader = is_equal(packet.param1, 3.0f);
-    hal.scheduler->reboot(hold_in_bootloader);
+
+    AP::vehicle()->reboot(hold_in_bootloader);  // not expected to return
 
     return MAV_RESULT_FAILED;
 }