MC land detector: remove LNDMC_THR_RANGE param

- no airframe changes the default
- it does not make much sense to be able to configure the 0.1 threshold
  but the 0.3 threshold for ground contact detection cannot be configured.

src/modules/land_detector/MulticopterLandDetector.cpp

@@ -75,7 +75,6 @@ MulticopterLandDetector::MulticopterLandDetector()
 	_paramHandle.maxRotation = param_find("LNDMC_ROT_MAX");
 	_paramHandle.maxVelocity = param_find("LNDMC_XY_VEL_MAX");
 	_paramHandle.maxClimbRate = param_find("LNDMC_Z_VEL_MAX");
-	_paramHandle.throttleRange = param_find("LNDMC_THR_RANGE");
 	_paramHandle.minThrottle = param_find("MPC_THR_MIN");
 	_paramHandle.hoverThrottle = param_find("MPC_THR_HOVER");
 	_paramHandle.minManThrottle = param_find("MPC_MANTHR_MIN");
@@ -121,7 +120,6 @@ void MulticopterLandDetector::_update_params()
 	_params.maxRotation_rad_s = math::radians(_params.maxRotation_rad_s);
 	param_get(_paramHandle.minThrottle, &_params.minThrottle);
 	param_get(_paramHandle.hoverThrottle, &_params.hoverThrottle);
-	param_get(_paramHandle.throttleRange, &_params.throttleRange);
 	param_get(_paramHandle.minManThrottle, &_params.minManThrottle);
 	param_get(_paramHandle.freefall_acc_threshold, &_params.freefall_acc_threshold);
 	param_get(_paramHandle.freefall_trigger_time, &_params.freefall_trigger_time);
@@ -320,7 +318,7 @@ bool MulticopterLandDetector::_has_low_thrust()
 bool MulticopterLandDetector::_has_minimal_thrust()
 {
 	// 10% of throttle range between min and hover once we entered ground contact
-	float sys_min_throttle = _params.minThrottle + (_params.hoverThrottle - _params.minThrottle) * _params.throttleRange;
+	float sys_min_throttle = _params.minThrottle + (_params.hoverThrottle - _params.minThrottle) * 0.1f;
 
 	// Determine the system min throttle based on flight mode
 	if (!_control_mode.flag_control_climb_rate_enabled) {

src/modules/land_detector/MulticopterLandDetector.h

@@ -101,7 +101,6 @@ private:
 		param_t maxRotation;
 		param_t minThrottle;
 		param_t hoverThrottle;
-		param_t throttleRange;
 		param_t minManThrottle;
 		param_t freefall_acc_threshold;
 		param_t freefall_trigger_time;
@@ -115,7 +114,6 @@ private:
 		float maxRotation_rad_s;
 		float minThrottle;
 		float hoverThrottle;
-		float throttleRange;
 		float minManThrottle;
 		float freefall_acc_threshold;
 		float freefall_trigger_time;

src/modules/land_detector/land_detector_params_mc.c

@@ -81,22 +81,6 @@ PARAM_DEFINE_FLOAT(LNDMC_ROT_MAX, 20.0f);
  */
 PARAM_DEFINE_FLOAT(LNDMC_FFALL_THR, 2.0f);
 
-/**
- * Multicopter sub-hover throttle scaling
- *
- * The range between throttle_min and throttle_hover is scaled
- * by this parameter to define how close to minimum throttle
- * the current throttle value needs to be in order to get
- * accepted as landed.
- *
- * @min 0.05
- * @max 0.5
- * @decimal 2
- *
- * @group Land Detector
- */
-PARAM_DEFINE_FLOAT(LNDMC_THR_RANGE, 0.1f);
-
 /**
  * Multicopter free-fall trigger time
  *