LU-4478 ldiskfs: fix problem when ldiskfs_acct_on() fails

LU-4478 ldiskfs: fix problem when ldiskfs_acct_on() fails

ldiskfs_fill_super() does not handle the failure that
ldiskfs_acct_on() returns correctly. This patch fixes
the problem.

Signed-off-by: Li Xi <lixi@ddn.com>
Change-Id: I70afca523cee1d9fe7e0b9c5ffc122fbfd6c34aa
Reviewed-on: http://review.whamcloud.com/8829
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>