co-queue: drop extra coroutine_fn marks

qemu_co_queue_next() and qemu_co_queue_restart_all() just call
aio_co_wake() which works well in non-coroutine context. So these
functions can be called from non-coroutine context as well. And
actually qemu_co_queue_restart_all() is called from
nbd_cancel_in_flight(), which is called from non-coroutine context.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210610100802.5888-2-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

include/qemu/coroutine.h

@@ -210,13 +210,15 @@ void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lock);
 /**
  * Removes the next coroutine from the CoQueue, and wake it up.
  * Returns true if a coroutine was removed, false if the queue is empty.
+ * OK to run from coroutine and non-coroutine context.
  */
-bool coroutine_fn qemu_co_queue_next(CoQueue *queue);
+bool qemu_co_queue_next(CoQueue *queue);
 
 /**
  * Empties the CoQueue; all coroutines are woken up.
+ * OK to run from coroutine and non-coroutine context.
  */
-void coroutine_fn qemu_co_queue_restart_all(CoQueue *queue);
+void qemu_co_queue_restart_all(CoQueue *queue);
 
 /**
  * Removes the next coroutine from the CoQueue, and wake it up.  Unlike