cu_up: fix N3 ext_bind_addr config

Author: robertfalkenberg

apps/units/o_cu_up/o_cu_up_builder.cpp

@@ -96,6 +96,7 @@ o_cu_up_unit srsran::build_o_cu_up(const o_cu_up_unit_config& unit_cfg, const o_
       udp_network_gateway_config n3_udp_cfg = {};
       n3_udp_cfg.bind_address               = sock_cfg.bind_addr;
       n3_udp_cfg.bind_interface             = sock_cfg.bind_interface;
+      n3_udp_cfg.ext_bind_addr              = sock_cfg.ext_addr;
       n3_udp_cfg.pool_occupancy_threshold   = sock_cfg.udp_config.pool_threshold;
       n3_udp_cfg.bind_port                  = GTPU_PORT;
       n3_udp_cfg.rx_max_mmsg                = sock_cfg.udp_config.rx_max_msgs;