blk-throttle: remove repeat check of elapsed time

There is no need to check elapsed time from last upgrade for each node in
hierarchy. Move this check before traversing as throtl_can_upgrade do
to remove repeat check.

Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-9-shikemeng@huaweicloud.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>