cpuset: remove dead code in cpuset-v1.c

cpuset: remove dead code in cpuset-v1.c

The commit 6e1d31ce495c ("cpuset: separate generate_sched_domains for v1
and v2") introduced dead code that was originally added for cpuset-v2
partition domain generation. Remove the redundant root_load_balance check.

Fixes: 6e1d31ce495c ("cpuset: separate generate_sched_domains for v1 and v2")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/cgroups/9a442808-ed53-4657-988b-882cc0014c0d@huaweicloud.com/T/
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>