cpuset: use seq_*mask_* to print masks

1) seq_file excepts that m->count == m->size when it's buf is full,
so current code will causes bugs when buf is overflow.

2) There is not too good that cpuset accesses struct seq_file's
fields directly.

Signed-off-by: Lai Jiangshan <[e-mail]>
Cc: Alexey Dobriyan <[e-mail]>
Acked-by: Paul Menage <[e-mail]>
Cc: Paul Jackson <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/cpuset.c

···
 void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
 {
 	seq_printf(m, "Cpus_allowed:\t");
-	m->count += cpumask_scnprintf(m->buf + m->count, m->size - m->count,
-					task->cpus_allowed);
+	seq_cpumask(m, &task->cpus_allowed);
 	seq_printf(m, "\n");
 	seq_printf(m, "Cpus_allowed_list:\t");
-	m->count += cpulist_scnprintf(m->buf + m->count, m->size - m->count,
-					task->cpus_allowed);
+	seq_cpumask_list(m, &task->cpus_allowed);
 	seq_printf(m, "\n");
 	seq_printf(m, "Mems_allowed:\t");
-	m->count += nodemask_scnprintf(m->buf + m->count, m->size - m->count,
-					task->mems_allowed);
+	seq_nodemask(m, &task->mems_allowed);
 	seq_printf(m, "\n");
 	seq_printf(m, "Mems_allowed_list:\t");
-	m->count += nodelist_scnprintf(m->buf + m->count, m->size - m->count,
-					task->mems_allowed);
+	seq_nodemask_list(m, &task->mems_allowed);
 	seq_printf(m, "\n");
 }