added thread-pool support for TX symbol processing

removed warnings in nr_dlsch.c and changed return of do_onelayer

Co-authored-by: Robert Schmidt <robert.schmidt@openairinterface.org>

openair1/SIMULATION/NR_PHY/dlsim.c

@@ -715,6 +715,7 @@ int main(int argc, char **argv)
 
   AssertFatal((gNB->if_inst = NR_IF_Module_init(0)) != NULL, "Cannot register interface");
   gNB->if_inst->NR_PHY_config_req = nr_phy_config_request;
+  gNB->num_pdsch_symbols_per_thread = 1;
 
   NR_ServingCellConfigCommon_t *scc = calloc(1,sizeof(*scc));;
   prepare_scc(scc);