LU-952 quota: follow locking order of quota code

LU-952 quota: follow locking order of quota code

The locking order of quota code is: i_mutex > dqonoff_sem >
journal_lock > dqptr_sem > dquot->dq_lock > dqio_mutex, so we
should call the ll_vfs_dq_init() after journal started to avoid
deadlock.

Signed-off-by: Niu Yawei <niu@whamcloud.com>
Change-Id: Ia88a2eb8c9dc3827afd4828e0160ee376a1f041e
Reviewed-on: http://review.whamcloud.com/1923
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>