VirtualJoystick: remove sub from yAxisPositiveRangeOnly condition (#9204)

Sub currently handles throttle in the 0-1000 range
https://github.com/ArduPilot/ardupilot/issues/8818

src/FlightDisplay/VirtualJoystick.qml

@@ -41,7 +41,7 @@ Item {
         anchors.bottom:         parent.bottom
         width:                  parent.height
         height:                 parent.height
-        yAxisPositiveRangeOnly: _activeVehicle && !_activeVehicle.rover && !_activeVehicle.sub
+        yAxisPositiveRangeOnly: _activeVehicle && !_activeVehicle.rover
         yAxisReCenter:          autoCenterThrottle
     }