LU-3065 osd: move delete agent inode before delete entry

LU-3065 osd: move delete agent inode before delete entry

Move deleting agent inode before deleting entry, so it will
not access the ino in bh after it has been freed.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ia750a0d2399717466d3e65865e5290ada60a7cb0
Reviewed-on: http://review.whamcloud.com/5884
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>