Remove dangerous _primary_hgt_source variable

EKF/ekf.cpp

@@ -177,11 +177,6 @@ bool Ekf::initialiseFilter()
 		}
 	}
 
-	// set the default height source from the adjustable parameter
-	if (_hgt_counter == 0) {
-		_primary_hgt_source = _params.vdist_sensor_type;
-	}
-
 	// accumulate enough height measurements to be confident in the quality of the data
 	// we use baro height initially and switch to GPS/range/EV finder later when it passes checks.
 	if (_baro_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_baro_sample_delayed)) {

EKF/ekf.h

@@ -505,7 +505,6 @@ private:
 	bool _baro_hgt_faulty{false};		///< true if valid baro data is unavailable for use
 	bool _gps_hgt_intermittent{false};	///< true if gps height into the buffer is intermittent
 	bool _rng_hgt_valid{false};		///< true if range finder sample retrieved from buffer is valid
-	int _primary_hgt_source{VDIST_SENSOR_BARO};	///< specifies primary source of height data
 	uint64_t _time_bad_rng_signal_quality{0};	///< timestamp at which range finder signal quality was 0 (used for hysteresis)
 
 	// imu fault status

EKF/gps_checks.cpp

@@ -90,7 +90,7 @@ bool Ekf::collect_gps(const gps_message &gps)
 		_gps_origin_epv = gps.epv;
 
 		// if the user has selected GPS as the primary height source, switch across to using it
-		if (_primary_hgt_source == VDIST_SENSOR_GPS) {
+		if (_params.vdist_sensor_type == VDIST_SENSOR_GPS) {
 			ECL_INFO_TIMESTAMPED("EKF GPS checks passed (WGS-84 origin set, using GPS height)");
 			_control_status.flags.baro_hgt = false;
 			_control_status.flags.gps_hgt = true;