Consolidate tasklet + tasklet-hi code

From: Sebastian Andrzej Siewior
Date: Thu Feb 15 2018 - 12:21:23 EST


Ingo made a RT patch a few years back called "tasklet: Prevent tasklets
from going into infinite spin in RT" [0]. I ripped the non-RT pieces out
of it and here they are. I kept him as the original Author.

[0] https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches/tasklet-rt-prevent-tasklets-from-going-into-infinite-spin-in-rt.patch?h=linux-4.14.y-rt-patches

Sebastian