LU-6305 osd-ldiskfs: buffer head leak in osd

iam_new_leaf() should release new_leaf
in case of an error

Change-Id: I48d358cb823d83b5412a1e4b88ab3ea13a0bee35
Xyratex-bug-id: MRP-2338
Signed-off-by: Andriy Skulysh <andriy.skulysh@seagate.com>
Reviewed-by: Alexey Lyashkov <alexey.lyashkov@seagate.com>
Reviewed-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Reviewed-on: http://review.whamcloud.com/13909


Tested-by: Jenkins
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>