Use nr_cpu_ids instead of nr_cpumask_bits to check the return value of cpumask_next

It should be check the return value with nr_cpu_ids according to the
comments of both of the cpumask_first and cpumask_next.

Certainly the nr_cpumask_bits has same value as nr_cpu_ids by its definition.
But we should follow the rule of kernel, all of caller in kernel
always use the nr_cpu_ids, not nr_cpumask_bits.