AP_Soaring: correct compiler warnings

In file included from ../../libraries/AP_Soaring/AP_Soaring.cpp:1:
../../libraries/AP_Soaring/AP_Soaring.h:32:34: warning: private field
'_aparm' is not used [-Wunused-private-field]
    const AP_Vehicle::FixedWing &_aparm;

libraries/AP_Soaring/AP_Soaring.cpp

@@ -131,8 +131,7 @@ const AP_Param::GroupInfo SoaringController::var_info[] = {
 SoaringController::SoaringController(AP_AHRS &ahrs, AP_SpdHgtControl &spdHgt, const AP_Vehicle::FixedWing &parms) :
     _ahrs(ahrs),
     _spdHgt(spdHgt),
-    _aparm(parms),
-    _vario(ahrs,spdHgt,parms),
+    _vario(ahrs,parms),
     _loiter_rad(parms.loiter_radius),
     _throttle_suppressed(true)
 {

libraries/AP_Soaring/AP_Soaring.h

@@ -29,7 +29,6 @@ class SoaringController {
     ExtendedKalmanFilter _ekf{};
     AP_AHRS &_ahrs;
     AP_SpdHgtControl &_spdHgt;
-    const AP_Vehicle::FixedWing &_aparm;
     Variometer _vario;
 
     // store aircraft location at last update

libraries/AP_Soaring/Variometer.cpp

@@ -4,9 +4,8 @@ Manages the estimation of aircraft total energy, drag and vertical air velocity.
 */
 #include "Variometer.h"
 
-Variometer::Variometer(AP_AHRS &ahrs, AP_SpdHgtControl &spdHgt, const AP_Vehicle::FixedWing &parms) :
+Variometer::Variometer(AP_AHRS &ahrs, const AP_Vehicle::FixedWing &parms) :
     _ahrs(ahrs),
-    _spdHgt(spdHgt),
     _aparm(parms),
     new_data(false)
 {

libraries/AP_Soaring/Variometer.h

@@ -17,7 +17,6 @@ Manages the estimation of aircraft total energy, drag and vertical air velocity.
 class Variometer {
 
     AP_AHRS &_ahrs;
-    AP_SpdHgtControl &_spdHgt;
     const AP_Vehicle::FixedWing &_aparm;
 
     // store time of last update
@@ -31,7 +30,7 @@ class Variometer {
     float _last_total_E;
 
 public:
-    Variometer(AP_AHRS &ahrs, AP_SpdHgtControl &spdHgt, const AP_Vehicle::FixedWing &parms);
+    Variometer(AP_AHRS &ahrs, const AP_Vehicle::FixedWing &parms);
     float alt;
     float reading;
     float filtered_reading;