EKF drop unused timestamp from collect_gps() and pass data by const reference

EKF/estimator_interface.h

@@ -169,7 +169,7 @@ public:
 	virtual void get_ekf_ctrl_limits(float *vxy_max, float *vz_max, float *hagl_min, float *hagl_max) = 0;
 
 	// ask estimator for sensor data collection decision and do any preprocessing if required, returns true if not defined
-	virtual bool collect_gps(uint64_t time_usec, struct gps_message *gps) { return true; }
+	virtual bool collect_gps(const gps_message &gps) = 0;
 
 	// accumulate and downsample IMU data to the EKF prediction rate
 	virtual bool collect_imu(const imuSample &imu) = 0;
@@ -184,7 +184,7 @@ public:
 	void setMagData(uint64_t time_usec, float (&data)[3]);
 
 	// set gps data
-	void setGpsData(uint64_t time_usec, struct gps_message *gps);
+	void setGpsData(uint64_t time_usec, const gps_message &gps);
 
 	// set baro data
 	void setBaroData(uint64_t time_usec, float data);