Planning: keep dp_st_graph params consistent.

modules/planning/conf/planning_config.pb.txt

@@ -36,8 +36,8 @@ em_planner_config {
         navigator_sample_num_each_level: 3
     }
     dp_st_speed_config {
-        total_path_length: 150
-        total_time: 8.0
+        total_path_length: 149
+        total_time: 7.0
         matrix_dimension_s: 150
         matrix_dimension_t: 8
 

modules/planning/tasks/dp_st_speed/dp_st_graph.cc

@@ -73,9 +73,9 @@ DpStGraph::DpStGraph(const StGraphData& st_graph_data,
       std::fmin(dp_st_speed_config_.total_path_length(),
                 st_graph_data_.path_data_length()));
   unit_s_ = dp_st_speed_config_.total_path_length() /
-            dp_st_speed_config_.matrix_dimension_s();
+            (dp_st_speed_config_.matrix_dimension_s() - 1);
   unit_t_ = dp_st_speed_config_.total_time() /
-            dp_st_speed_config_.matrix_dimension_t();
+            (dp_st_speed_config_.matrix_dimension_t() - 1);
 }
 
 Status DpStGraph::Search(SpeedData* const speed_data) {