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/include/openbsc/bsc_msc.h b/openbsc/include/openbsc/bsc_msc.h
index 88f0de4..9543002 100644
--- a/openbsc/include/openbsc/bsc_msc.h
+++ b/openbsc/include/openbsc/bsc_msc.h
@@ -35,7 +35,7 @@
 
 
 struct bsc_msc_connection {
-	struct write_queue write_queue;
+	struct osmo_wqueue write_queue;
 	int is_connected;
 	int is_authenticated;
 	int first_contact;