block: export passthrough stats enabled

block: export passthrough stats enabled

A user can enable io accounting for passthrough requests, so export the
helper that checks if the request should be tracked. This will enable
stacking drivers to to report iostats for passthrough workloads. Since
the stacking request_queue may not be the one providing the request, the
API has to add a parameter for the caller to specify which one to check.

Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260528010041.1533124-2-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>