uorb callbacks: fix unregister ordering to avoid race conditions

The order should be: first unregister, then remove the item from the
runnable queue.

src/modules/sensors/vehicle_acceleration/VehicleAcceleration.cpp

@@ -71,14 +71,14 @@ bool VehicleAcceleration::Start()
 
 void VehicleAcceleration::Stop()
 {
-	Deinit();
-
 	// clear all registered callbacks
 	for (auto &sub : _sensor_sub) {
 		sub.unregisterCallback();
 	}
 
 	_sensor_selection_sub.unregisterCallback();
+
+	Deinit();
 }
 
 void VehicleAcceleration::CheckFilters()

src/modules/sensors/vehicle_angular_velocity/VehicleAngularVelocity.cpp

@@ -74,14 +74,14 @@ bool VehicleAngularVelocity::Start()
 
 void VehicleAngularVelocity::Stop()
 {
-	Deinit();
-
 	// clear all registered callbacks
 	for (auto &sub : _sensor_sub) {
 		sub.unregisterCallback();
 	}
 
 	_sensor_selection_sub.unregisterCallback();
+
+	Deinit();
 }
 
 void VehicleAngularVelocity::CheckFilters()

src/modules/sensors/vehicle_imu/VehicleIMU.cpp

@@ -66,11 +66,11 @@ bool VehicleIMU::Start()
 
 void VehicleIMU::Stop()
 {
-	Deinit();
-
 	// clear all registered callbacks
 	_sensor_accel_integrated_sub.unregisterCallback();
 	_sensor_gyro_integrated_sub.unregisterCallback();
+
+	Deinit();
 }
 
 void VehicleIMU::ParametersUpdate(bool force)