Revert "block: reduce kblockd_mod_delayed_work_on() CPU consumption"

This reverts commit cb2ac291.

Alex and the kernel test robot report that this causes a significant
performance regression with BFQ. I can reproduce that result, so let's
revert this one as we're close to -rc6 and we there's no point in trying
to rush a fix.

Link: https://lore.kernel.org/linux-block/1639853092.524jxfaem2.none@localhost/
Link: https://lore.kernel.org/lkml/20211219141852.GH14057@xsang-OptiPlex-9020/


Reported-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>