nat: Assign the connection inside the new helper function.

openbsc/src/nat/bsc_nat.c

@@ -543,7 +543,6 @@ static int ipaccess_listen_bsc_cb(struct bsc_fd *bfd, unsigned int what)
 		return -1;
 	}
 
-	bsc->nat = nat;
 	write_queue_init(&bsc->write_queue, 100);
 	bsc->write_queue.bfd.data = bsc;
 	bsc->write_queue.bfd.fd = ret;

openbsc/src/nat/bsc_nat_utils.c

@@ -45,6 +45,7 @@ struct bsc_connection *bsc_connection_alloc(struct bsc_nat *nat)
 	if (!con)
 		return NULL;
 
+	con->nat = nat;
 	return con;
 }