fs: remove bdev_try_to_free_page callback

mainline inclusion
from mainline-5.14-rc1
commit acc6100d
category: bugfix
bugzilla: 50788
CVE: NA
---------------------------

After remove the unique user of sop->bdev_try_to_free_page() callback,
we could remove the callback and the corresponding blkdev_releasepage()
at all.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210610112440.3438139-9-yi.zhang@huawei.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Conflict:
  [keep bdev_try_to_free_page() interface for ABI.]
  include/linux/fs.h
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>