correct name number_of_spline to number_of_knots (#380)

modules/planning/conf/qp_spline_path_config.pb.txt

 spline_order: 6
-number_of_spline: 5
+number_of_knots: 5
 number_of_fx_constraint_knots: 13
 time_resolution: 0.1
 regularization_weight: 0.001

modules/planning/optimizer/qp_spline_path/qp_spline_path_sampler.cc

@@ -58,14 +58,14 @@ bool QpSplinePathSampler::Sample(const common::FrenetFramePoint& init_point,
   sampling_point->emplace_back(start_s);
 
   // map sampling point
-  if (config_.number_of_spline() == 0) {
+  if (config_.number_of_knots() == 0) {
     AERROR << "sampling point shall greater than 0";
     return false;
   }
-  const double delta_s = sampling_distance / config_.number_of_spline();
+  const double delta_s = sampling_distance / config_.number_of_knots();
 
   double s = start_s + delta_s;
-  for (uint32_t i = 1; i <= config_.number_of_spline(); ++i) {
+  for (uint32_t i = 1; i <= config_.number_of_knots(); ++i) {
     sampling_point->emplace_back(s);
     s += delta_s;
   }

modules/planning/proto/qp_spline_path_config.proto

@@ -4,7 +4,7 @@ package apollo.planning;
 
 message QpSplinePathConfig {
   optional uint32 spline_order = 1 [default = 6];
-  optional uint32 number_of_spline = 2 [default = 5];
+  optional uint32 number_of_knots = 2 [default = 5];
   optional uint32 number_of_fx_constraint_knots = 3 [default = 6];
   optional double time_resolution = 4 [default = 0.1];
   optional double regularization_weight = 5 [default = 0.001];

modules/planning/testdata/conf/qp_spline_path_config.pb.txt

 spline_order: 6
-number_of_spline: 5
+number_of_knots: 5
 number_of_fx_constraint_knots: 13
 time_resolution: 0.1
 regularization_weight: 0.001