LU-6158 mdt: always shrink_capsule in getxattr_all

LU-6158 mdt: always shrink_capsule in getxattr_all

When mdt_getxattr_one returns error, capsule should be
shrunk to zero before exit in mdt_getxattr_all.

Change-Id: I060fd74177b5d7647581bda9cdb83937ab6a74a8
Signed-off-by: Sergey Cheremencev <sergey.cheremencev@seagate.com>
Signed-off-by: Alexander Zarochentsev <alexander.zarochentsev@seagate.com>
Xyratex-bug-id: MRP-2340
Reviewed-on: http://review.whamcloud.com/13524
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>