cgroup/cpuset: Miscellaneous code cleanup

cgroup/cpuset: Miscellaneous code cleanup

BugLink: https://bugs.launchpad.net/bugs/1946788
[ Upstream commit 0f3adb8a1e5f36e792598c1d77a2cfac9c90a4f9 ]

Use more descriptive variable names for update_prstate(), remove
unnecessary code and fix some typos. There is no functional change.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>