jbd2: remove __journal_try_to_free_buffer()

__journal_try_to_free_buffer() has only one caller and it's logic is
much simple now, so just remove it and open code in
jbd2_journal_try_to_free_buffers().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230606135928.434610-7-yi.zhang@huaweicloud.com


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