MRP-1296 ldlm: ldlm_cancel_stale_locks()) ASSERTION( count > 0 ) failed

number of granted locks can be really huge.
Use 64bit math to calculate number of locks to cancel

Change-Id: Ia10c056a03750c242e6bb97dfad5718d54fe7e88
Signed-off-by: Andriy Skulysh <Andriy_Skulysh@xyratex.com>
Reviewed-on: http://morpheus.xyus.xyratex.com:8443/gerrit/637
Reviewed-by: Alexey Lyashkov <Alexey_Lyashkov@xyratex.com>
Tested-by: Jenkins
Reviewed-by: Alexander Boyko <Alexander_Boyko@xyratex.com>
Tested-by: Elena Gryaznova <Elena_Gryaznova@xyratex.com>
Reviewed-by: Vitaly Fertman <Vitaly_Fertman@xyratex.com>