src: use namespace prefix osmo_wqueue*

Summary of changes:

s/struct write_queue/struct osmo_wqueue/g
s/write_queue_init/osmo_wqueue_init/g
s/write_queue_clear/osmo_wqueue_clear/g
s/write_queue_enqueue/osmo_wqueue_enqueue/g
s/write_queue_bfd_cb/osmo_wqueue_bfd_cb/g
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 0fb5843..f732488 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -100,7 +100,7 @@
 	}
 
 
-	if (write_queue_enqueue(&con->write_queue, msg) != 0) {
+	if (osmo_wqueue_enqueue(&con->write_queue, msg) != 0) {
 		LOGP(DINP, LOGL_ERROR, "Failed to enqueue the write.\n");
 		msgb_free(msg);
 	}
@@ -877,7 +877,7 @@
 
 	osmo_fd_unregister(&connection->write_queue.bfd);
 	close(connection->write_queue.bfd.fd);
-	write_queue_clear(&connection->write_queue);
+	osmo_wqueue_clear(&connection->write_queue);
 	llist_del(&connection->list_entry);
 
 	talloc_free(connection);