polish api_gen parameter in CMakeLists (#50573)

paddle/phi/api/lib/CMakeLists.txt

@@ -108,8 +108,7 @@ add_custom_command(
   COMMAND
     ${PYTHON_EXECUTABLE} ${api_gen_file} --api_yaml_path ${api_yaml_file}
     ${legacy_api_yaml_file} --api_header_path ${api_header_file_tmp}
-    --api_header_path ${api_header_file_tmp} --api_source_path
-    ${api_source_file_tmp}
+    --api_source_path ${api_source_file_tmp}
   COMMAND ${CMAKE_COMMAND} -E copy_if_different ${api_header_file_tmp}
           ${api_header_file}
   COMMAND ${CMAKE_COMMAND} -E copy_if_different ${api_source_file_tmp}