uavcan: support uavcan hygrometer

src/drivers/uavcan/uavcan_params.c

@@ -275,6 +275,18 @@ PARAM_DEFINE_INT32(UAVCAN_SUB_FLOW, 0);
  */
 PARAM_DEFINE_INT32(UAVCAN_SUB_GPS, 1);
 
+/**
+ * subscription hygrometer
+ *
+ * Enable UAVCAN hygrometer subscriptions.
+ *  dronecan::sensors::hygrometer::Hygrometer
+ *
+ * @boolean
+ * @reboot_required true
+ * @group UAVCAN
+ */
+PARAM_DEFINE_INT32(UAVCAN_SUB_HYGRO, 0);
+
 /**
  * subscription ICE
  *