uORB::Publication simplify and cleanup

- base class is now template
 - drop linked list
 - virtualization no longer required

src/lib/drivers/accelerometer/PX4Accelerometer.hpp

@@ -68,7 +68,7 @@ private:
 
 	void configure_filter(float cutoff_freq) { _filter.set_cutoff_frequency(_sample_rate, cutoff_freq); }
 
-	uORB::Publication<sensor_accel_s>	_sensor_accel_pub;
+	uORB::PublicationData<sensor_accel_s>	_sensor_accel_pub;
 
 	math::LowPassFilter2pVector3f _filter{1000, 100};
 	Integrator _integrator{4000, false};

src/lib/drivers/barometer/PX4Barometer.hpp

@@ -59,7 +59,7 @@ public:
 
 private:
 
-	uORB::Publication<sensor_baro_s>	_sensor_baro_pub;
+	uORB::PublicationData<sensor_baro_s>	_sensor_baro_pub;
 
 	int			_class_device_instance{-1};
 

src/lib/drivers/gyroscope/PX4Gyroscope.hpp

@@ -68,7 +68,7 @@ private:
 
 	void configure_filter(float cutoff_freq) { _filter.set_cutoff_frequency(_sample_rate, cutoff_freq); }
 
-	uORB::Publication<sensor_gyro_s>	_sensor_gyro_pub;
+	uORB::PublicationData<sensor_gyro_s>	_sensor_gyro_pub;
 
 	math::LowPassFilter2pVector3f _filter{1000, 100};
 	Integrator _integrator{4000, true};

src/lib/drivers/magnetometer/PX4Magnetometer.hpp

@@ -63,7 +63,7 @@ public:
 
 private:
 
-	uORB::Publication<sensor_mag_s>	_sensor_mag_pub;
+	uORB::PublicationData<sensor_mag_s>	_sensor_mag_pub;
 
 	const enum Rotation	_rotation;