LU-4825 ofd: fix OBD_FAIL_OST_ENOINO/ENOSPC behaviour

LU-4825 ofd: fix OBD_FAIL_OST_ENOINO/ENOSPC behaviour

Fix the OBD_FAIL_OST_ENOINO and OBD_FAIL_OST_ENOSPC behaviour so that
they also reduce the total number of inodes or blocks when setting the
number of free inodes/blocks to zero.  This allows "lfs df [-i]" to
still report the correct number of blocks and inodes used on the OST.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Ia746273e19aed22a0926708899de009b8d5cab07
Reviewed-on: https://review.whamcloud.com/20163
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>