write-queue: use namespace prefix osmo_wqueue*

write-queue: 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/void 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