delete drv_baro.h, drv_mag.h, drv_range_finder.h, drv_device.h and purge UAVCAN CDev usage

src/drivers/optical_flow/px4flow/px4flow.cpp

@@ -41,7 +41,6 @@
 
 #include <drivers/device/i2c.h>
 #include <drivers/drv_hrt.h>
-#include <drivers/drv_range_finder.h>
 #include <lib/conversion/rotation.h>
 #include <lib/parameters/param.h>
 #include <lib/perf/perf_counter.h>
@@ -101,8 +100,6 @@ private:
 	uint8_t _sonar_rotation;
 	bool				_sensor_ok{false};
 	bool				_collect_phase{false};
-	int			_class_instance{-1};
-	int			_orb_class_instance{-1};
 
 	uORB::PublicationMulti<optical_flow_s>		_px4flow_topic{ORB_ID(optical_flow)};
 	uORB::PublicationMulti<distance_sensor_s>	_distance_sensor_topic{ORB_ID(distance_sensor)};
@@ -169,8 +166,6 @@ PX4FLOW::init()
 		return ret;
 	}
 
-	_class_instance = register_class_devname(RANGE_FINDER_BASE_DEVICE_PATH);
-
 	ret = OK;
 	/* sensor is ok, but we don't really know if it is within range */
 	_sensor_ok = true;
@@ -316,7 +311,7 @@ PX4FLOW::collect()
 	_px4flow_topic.publish(report);
 
 	/* publish to the distance_sensor topic as well */
-	if (_class_instance == CLASS_DEVICE_PRIMARY) {
+	if (_distance_sensor_topic.get_instance() == 0) {
 		distance_sensor_s distance_report{};
 		distance_report.timestamp = report.timestamp;
 		distance_report.min_distance = PX4FLOW_MIN_DISTANCE;