jbd2: remove j_format_version

journal->j_format_version is no longer used, remove it.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230315013128.3911115-7-chengzhihao1@huawei.com


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