block: remove elv_abort_queue and blk_abort_flushes

elv_abort_queue has no callers, and blk_abort_flushes is only called by
elv_abort_queue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --cc block/blk-flush.c
Simple merge

diff --cc block/blk.h
Simple merge

diff --cc block/elevator.c
Simple merge

diff --cc include/linux/elevator.h
Simple merge