scheduler: Fix reverting CPU affinity in process groups

Previously CPU affinity of tasks created while Tuned was running
was not correctly reverted on Tuned shutdown.

Reproducer (on a 4 core machine):
$ mkdir /etc/tuned/test
$ cat > /etc/tuned/test/tuned.conf << EOF
[scheduler]
group.foo=0⭕0:1:a.out
EOF
$ cat > a.c << EOF
 #include <unistd.h>

int main(void)
{
	pause();
	return 0;
}
EOF
$ gcc a.c
$ systemctl start tuned
$ ./a.out &
$ systemctl stop tuned
$ taskset -p $(pgrep a.out)
pid 9950's current affinity mask: 1  <<< should be "f"

Known issue: if you run the above reproducer with the config below
after this commit is applied, the affinity of the task after stopping
tuned will be 0xd, not 0xf. This is because after starting tuned, first
the affinity of the shell session is set to the non-isolated cores (0xd).
Then when ./a.out starts, it inherits that affinity. Then when tuned tunes
the affinity of the ./a.out process, it remembers 0xd as its old affinity
rather than 0xf. It is unclear to me at this point whether we should do
anything about this issue. Properly fixing it would require tracing where
processes get their affinity from.

[scheduler]
group.foo=0⭕0:1:a.out
ps_blacklist=.*a.out.*
isolated_cores=1

Signed-off-by: Ondřej Lysoněk <olysonek@redhat.com>

tuned/plugins/plugin_scheduler.py

@@ -284,7 +284,7 @@ class SchedulerPlugin(base.Plugin):
 		for pid, vals in list(instance._scheduler_original.items()):
 			# if command line for the pid didn't change, it's very probably the same process
 			try:
-				if ps[pid] == vals[0]:
+				if ps[int(pid)] == vals[0]:
 					self._set_rt(pid, self._sched2param(vals[1]), vals[2])
 					self._set_affinity(pid, vals[3])
 			except KeyError as e: