block: correctly report cache type

Check the features flag and the override flag using the
blk_queue_write_cache, helper otherwise we're going to always
report "write through".

Fixes: 1122c0c1 ("block: move cache control settings out of queue->flags")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240626142637.300624-3-hch@lst.de


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