jbd2: remove the out label in __jbd2_journal_remove_checkpoint()

hulk inclusion
category: bugfix
bugzilla: 50788
CVE: NA
---------------------------

The 'out' lable just return the 'ret' value and seems not required, so
remove this label and switch to return appropriate value immediately.
This patch also do some minor cleanup, no logical change.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>