md/raid5: Replace deprecated CPU-hotplug functions.

The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().

Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20210803141621.780504-16-bigeasy@linutronix.de

drivers/md/raid5.c

@@ -2437,7 +2437,7 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
 	    conf->scribble_sectors >= new_sectors)
 		return 0;
 	mddev_suspend(conf->mddev);
-	get_online_cpus();
+	cpus_read_lock();
 
 	for_each_present_cpu(cpu) {
 		struct raid5_percpu *percpu;
@@ -2449,7 +2449,7 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
 			break;
 	}
 
-	put_online_cpus();
+	cpus_read_unlock();
 	mddev_resume(conf->mddev);
 	if (!err) {
 		conf->scribble_disks = new_disks;