staging/lustre/ldlm: move cancel_unused_locks_before_replay to sysfs

/proc/fs/lustre/ldlm/cancel_unused_locks_before_replay is
moved to /sys/fs/lustre/ldlm/cancel_unused_locks_before_replay

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>