selftest/cgroup: Update test_cpuset_prs.sh to use | as effective CPUs and state separator

Currently, ',' is used as the cgroup separator of the expected effective
CPUs and partition root states in the test matrix. However, ',' can be
part of the output of the cpuset.cpus*.effective and cpuset.cpus.isolated
files. Change the separator to '|' so that ',' can appear as part of
the expected values.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>