Apply default configuration for SRB1 when receiving RRCReestablishmentRequest

- according to 5.3.7.4 of TS 38.331

openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c

@@ -716,6 +716,8 @@ void dl_rrc_message_transfer(const f1ap_dl_rrc_message_t *dl_rrc)
     pthread_mutex_unlock(&mac->sched_lock);
     nr_rlc_remove_ue(dl_rrc->gNB_DU_ue_id);
     nr_rlc_update_id(*dl_rrc->old_gNB_DU_ue_id, dl_rrc->gNB_DU_ue_id);
+    /* 38.331 clause 5.3.7.4: apply the specified configuration defined in 9.2.1 for SRB1 */
+    nr_rlc_reconfigure_entity(dl_rrc->gNB_DU_ue_id, 1, NULL);
     instance_t f1inst = get_f1_gtp_instance();
     if (f1inst >= 0) // we actually use F1-U
       gtpv1u_update_ue_id(f1inst, *dl_rrc->old_gNB_DU_ue_id, dl_rrc->gNB_DU_ue_id);