block/mq-deadline: Move dd_queued() to fix defined but not used warning

block/mq-deadline: Move dd_queued() to fix defined but not used warning

If CONFIG_BLK_DEBUG_FS=n:

    block/mq-deadline.c:274:12: warning: ‘dd_queued’ defined but not used [-Wunused-function]
      274 | static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
	  |            ^~~~~~~~~

Fix this by moving dd_queued() just before the sole function that calls
it.

Fixes: 7b05bf771084ff78 ("Revert "block/mq-deadline: Prioritize high-priority requests"")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: 38ba64d12d4c ("block/mq-deadline: Track I/O statistics")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20210830091128.1854266-1-geert@linux-m68k.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>