x86: Add performance variants of cpumask operators

  * Increase performance for systems with large count NR_CPUS by limiting
    the range of the cpumask operators that loop over the bits in a cpumask_t
    variable.  This removes a large amount of wasted cpu cycles.

  * Add performance variants of the cpumask operators:

    int cpus_weight_nr(mask)	     Same using nr_cpu_ids instead of NR_CPUS
    int first_cpu_nr(mask)	     Number lowest set bit, or nr_cpu_ids
    int next_cpu_nr(cpu, mask)	     Next cpu past 'cpu', or nr_cpu_ids
    for_each_cpu_mask_nr(cpu, mask)  for-loop cpu over mask using nr_cpu_ids

  * Modify following to use performance variants:

    #define num_online_cpus()	cpus_weight_nr(cpu_online_map)
    #define num_possible_cpus()	cpus_weight_nr(cpu_possible_map)
    #define num_present_cpus()	cpus_weight_nr(cpu_present_map)

    #define for_each_possible_cpu(cpu) for_each_cpu_mask_nr((cpu), ...)
    #define for_each_online_cpu(cpu)   for_each_cpu_mask_nr((cpu), ...)
    #define for_e...