mc_att_control: move the board_rotation computation to the parameters_update

It's not necessary to do this computation in each loop iteration.

src/modules/mc_att_control/mc_att_control_main.cpp

@@ -664,6 +664,17 @@ MulticopterAttitudeControl::parameters_update()
 	param_get(_params_handles.board_offset[1], &(_params.board_offset[1]));
 	param_get(_params_handles.board_offset[2], &(_params.board_offset[2]));
 
+
+	/* get transformation matrix from sensor/board to body frame */
+	get_rot_matrix((enum Rotation)_params.board_rotation, &_board_rotation);
+
+	/* fine tune the rotation */
+	math::Matrix<3, 3> board_rotation_offset;
+	board_rotation_offset.from_euler(M_DEG_TO_RAD_F * _params.board_offset[0],
+					 M_DEG_TO_RAD_F * _params.board_offset[1],
+					 M_DEG_TO_RAD_F * _params.board_offset[2]);
+	_board_rotation = board_rotation_offset * _board_rotation;
+
 	return OK;
 }
 
@@ -979,16 +990,6 @@ MulticopterAttitudeControl::control_attitude_rates(float dt)
 		_rates_int.zero();
 	}
 
-	/* get transformation matrix from sensor/board to body frame */
-	get_rot_matrix((enum Rotation)_params.board_rotation, &_board_rotation);
-
-	/* fine tune the rotation */
-	math::Matrix<3, 3> board_rotation_offset;
-	board_rotation_offset.from_euler(M_DEG_TO_RAD_F * _params.board_offset[0],
-					 M_DEG_TO_RAD_F * _params.board_offset[1],
-					 M_DEG_TO_RAD_F * _params.board_offset[2]);
-	_board_rotation = board_rotation_offset * _board_rotation;
-
 	// get the raw gyro data and correct for thermal errors
 	math::Vector<3> rates;