cgroup/cpuset: remove unreachable code

The function sched_partition_show cannot execute seq_puts, delete the
invalid code.

kernel/cgroup/cpuset.c:2849 sched_partition_show() warn: ignoring unreachable code.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2087


Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>