block: Make blk_mq_get_sq_hctx() select the proper hardware queue type

Since the introduction of blk_mq_get_hctx_type() the operation type in
the second argument of blk_mq_get_hctx_type() matters. The introduction
of blk_mq_get_hctx_type() caused blk_mq_get_sq_hctx() to select a
hardware queue of type HCTX_TYPE_READ instead of HCTX_TYPE_DEFAULT.
Switch to hardware queue type HCTX_TYPE_DEFAULT since HCTX_TYPE_READ
should only be used for read requests.

Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220615225549.1054905-4-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>