jbd2: correct comment jbd2_mark_journal_empty

After jbd2_mark_journal_empty, journal log is supposed to be empty.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20240801013815.2393869-8-shikemeng@huaweicloud.com


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