quota: Move duplicated code to separate functions

- for(..) { mark_dquot_dirty(); } -> mark_all_dquot_dirty()
- for(..) { dput(); }             -> dqput_all()

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>