generic/230: reset grace time before overcome hardlimit

generic/230: reset grace time before overcome hardlimit

Currently, we call repquota to report the latest quota information
after each test case. But repquota will invoke Q_SYNC on the ext4 file
system with old quota, which may be time consuming on the low speed or
busy scratch device. If we call repquota between the "overcome
softlimit" and the "overcome hardlimit" cases, the softlimit grace time
may be exceed after repquota return, and lead to test failure.

Now, we capture the following failure when the disk is busy:

   pwrite: Disk quota exceeded
   Touch 3+4
   Touch 5+6
  +touch: cannot touch 'SCRATCH_MNT/file5': Disk quota exceeded
   touch: cannot touch 'SCRATCH_MNT/file6': Disk quota exceeded
   Touch 5
   touch: cannot touch 'SCRATCH_MNT/file5': Disk quota exceeded

This patch reset grace time before the "overcome hardlimit" case to
avoid this failure.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>