LU-7062 ldlm: GPF in _ldlm_lock_debug()

LU-7062 ldlm: GPF in _ldlm_lock_debug()

Lock's resource can change on a client.
Take a resource reference under spinlock
to print debug information.

Change-Id: Id8acb801ea549bf3c1ce1bcf6349db31578579f3
Xyratex-bug-id: MRP-2760
Signed-off-by: Andriy Skulysh <andriy.skulysh@seagate.com>
Reviewed-on: https://review.whamcloud.com/16139
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>