cpumask: Use nr_cpu_ids in seq_cpumask

Impact: cleanup, futureproof

nr_cpu_ids is the (badly named) runtime limit on possible CPU numbers;
ie. the variable version of NR_CPUS.

With the new cpumask operators, only bits less than this are defined.
So we should use it everywhere, rather than NR_CPUS.  Eventually this
will make it possible to allocate cpumasks of the minimal length at runtime.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NMike Travis <travis@sgi.com>
Acked-by: NIngo Molnar <mingo@elte.hu>

include/linux/seq_file.h

@@ -54,7 +54,7 @@ int seq_bitmap(struct seq_file *m, const unsigned long *bits,
 				   unsigned int nr_bits);
 static inline int seq_cpumask(struct seq_file *m, const struct cpumask *mask)
 {
-	return seq_bitmap(m, mask->bits, NR_CPUS);
+	return seq_bitmap(m, mask->bits, nr_cpu_ids);
 }
 
 static inline int seq_nodemask(struct seq_file *m, nodemask_t *mask)