block: Revert "block: Do not reread partition table on exclusively open device"

This reverts commit 36369f46

.

This patch can't fix the problem in a corner case that device can be
opened exclusively after the checking and before blkdev_get_by_dev().
We'll use a new solution to fix the problem in the next patch, and
the new solution doesn't need to change apis.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230217022200.3092987-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>