AP_InertialSensor: save only gyro calibration

When we are initializing the gyro and then saving the calibration we are
also saving the calibration values for the accelerometers. Right now
this is non-problematic, but we want to check that the ID of the
accelerometer corresponds to the ID of the sensor detected. If we also
save accel calibrations we would actually override the ID of the
accelerometer.

Rename the method to _save_gyro_calibration() and save only on gyro
values.

libraries/AP_InertialSensor/AP_InertialSensor.cpp

@@ -683,7 +683,7 @@ AP_InertialSensor::init_gyro()
     _init_gyro();
 
     // save calibration
-    _save_parameters();
+    _save_gyro_calibration();
 }
 
 // accelerometer clipping reporting
@@ -986,11 +986,9 @@ AP_InertialSensor::_init_gyro()
 }
 
 // save parameters to eeprom
-void AP_InertialSensor::_save_parameters()
+void AP_InertialSensor::_save_gyro_calibration()
 {
     for (uint8_t i=0; i<INS_MAX_INSTANCES; i++) {
-        _accel_scale[i].save();
-        _accel_offset[i].save();
         _gyro_offset[i].save();
     }
 }

libraries/AP_InertialSensor/AP_InertialSensor.h

@@ -272,8 +272,8 @@ private:
 
     bool _calculate_trim(const Vector3f &accel_sample, float& trim_roll, float& trim_pitch);
 
-    // save parameters to eeprom
-    void  _save_parameters();
+    // save gyro calibration values to eeprom
+    void _save_gyro_calibration();
 
     // backend objects
     AP_InertialSensor_Backend *_backends[INS_MAX_BACKENDS];