LU-4629 osd-ldiskfs: Fix use after free

LU-4629 osd-ldiskfs: Fix use after free

Object 'dir' was dereferenced at line 3343 after being freed
by calling 'kfree' at line 3332.

Lustre-commit: f4842b027ee57969fa1b01b90d5f23aed18b5eb5
Lustre-change: http://review.whamcloud.com/10609

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: I5e27f4555bda6144be5e5fcb9d0f00916512020a
Reviewed-on: http://review.whamcloud.com/12096
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>