commander: ignore arm/disarm in DO_SET_MODE cmd

According to https://github.com/mavlink/mavlink/pull/629 the mavlink
command DO_SET_MODE should only determine the mode but not the
armed/disarmed state, so the MAV_MODE_FLAG_SAFETY_ARMED bit should be
ignored.
Instead the mavlink command COMPONENT_ARM_DISARM should be used instead.

Therefore, the commander now ignores the arm/disarm bit.

src/modules/commander/commander.cpp

@@ -730,17 +730,9 @@ bool handle_command(struct vehicle_status_s *status_local, const struct safety_s
 			hil_state_t new_hil_state = (base_mode & VEHICLE_MODE_FLAG_HIL_ENABLED) ? vehicle_status_s::HIL_STATE_ON : vehicle_status_s::HIL_STATE_OFF;
 			transition_result_t hil_ret = hil_state_transition(new_hil_state, status_pub, status_local, &mavlink_log_pub);
 
-			// Transition the arming state
-			bool cmd_arm = base_mode & VEHICLE_MODE_FLAG_SAFETY_ARMED;
-
-			arming_ret = arm_disarm(cmd_arm, &mavlink_log_pub, "set mode command");
-
-			/* update home position on arming if at least 500 ms from commander start spent to avoid setting home on in-air restart */
-			if (cmd_arm && (arming_ret == TRANSITION_CHANGED) &&
-				(hrt_absolute_time() > (commander_boot_timestamp + INAIR_RESTART_HOLDOFF_INTERVAL))) {
-
-				commander_set_home_position(*home_pub, *home, *local_pos, *global_pos, *attitude);
-			}
+			// We ignore base_mode & VEHICLE_MODE_FLAG_SAFETY_ARMED because
+			// the command VEHICLE_CMD_COMPONENT_ARM_DISARM should be used
+			// instead according to the latest mavlink spec.
 
 			if (base_mode & VEHICLE_MODE_FLAG_CUSTOM_MODE_ENABLED) {
 				/* use autopilot-specific mode */