fmu: fix comments & documentation

src/drivers/px4fmu/fmu.cpp

@@ -134,9 +134,6 @@ public:
 	/** @see ModuleBase */
 	static int print_usage(const char *reason = nullptr);
 
-	/**
-	 * run the main loop: if running as task, continuously iterate, otherwise execute only one single cycle
-	 */
 	void Run() override;
 
 	/** @see ModuleBase::print_status() */
@@ -2600,11 +2597,7 @@ driver. Alternatively, the fmu can be started in one of the capture modes, and t
 callback with ioctl calls.
 
 ### Implementation
-By default the module runs on the work queue, to reduce RAM usage. It can also be run in its own thread,
-specified via start flag -t, to reduce latency.
-When running on the work queue, it schedules at a fixed frequency, and the pwm rate limits the update rate of
-the actuator_controls topics. In case of running in its own thread, the module polls on the actuator_controls topic.
-Additionally the pwm rate defines the lower-level IO timer rates.
+By default the module runs on a work queue with a callback on the uORB actuator_controls topic.
 
 ### Examples
 It is typically started with:
@@ -2622,7 +2615,6 @@ mixer files.
 
 	PRINT_MODULE_USAGE_NAME("fmu", "driver");
 	PRINT_MODULE_USAGE_COMMAND_DESCR("start", "Start the task (without any mode set, use any of the mode_* cmds)");
-	PRINT_MODULE_USAGE_PARAM_FLAG('t', "Run as separate task instead of the work queue", true);
 
 	PRINT_MODULE_USAGE_PARAM_COMMENT("All of the mode_* commands will start the fmu if not running already");