planning: update markdown latex equations in qp_spline_path_optimizer.md
planning: update markdown latex equations in qp_spline_path_optimizer.md

startcode/apollo,startcode/apollo,fy2462/apollo,fy2462/apollo,startcode/apollo,fy2462/apollo,startcode/apollo,startcode/apollo,startcode/apollo,fy2462/apollo,fy2462/apollo,fy2462/apollo