blk-mq: remove blk_mq_init_sq_queue

All users are gone now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210602065345.355274-16-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>