sgi-xpc: 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.

Cc: Robin Holt <robinmholt@gmail.com>
Cc: Steve Wahl <steve.wahl@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20210803141621.780504-17-bigeasy@linutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/sgi-xp/xpc_uv.c

@@ -1742,7 +1742,7 @@ xpc_init_mq_node(int nid)
 {
 	int cpu;
 
-	get_online_cpus();
+	cpus_read_lock();
 
 	for_each_cpu(cpu, cpumask_of_node(nid)) {
 		xpc_activate_mq_uv =
@@ -1753,7 +1753,7 @@ xpc_init_mq_node(int nid)
 			break;
 	}
 	if (IS_ERR(xpc_activate_mq_uv)) {
-		put_online_cpus();
+		cpus_read_unlock();
 		return PTR_ERR(xpc_activate_mq_uv);
 	}
 
@@ -1767,11 +1767,11 @@ xpc_init_mq_node(int nid)
 	}
 	if (IS_ERR(xpc_notify_mq_uv)) {
 		xpc_destroy_gru_mq_uv(xpc_activate_mq_uv);
-		put_online_cpus();
+		cpus_read_unlock();
 		return PTR_ERR(xpc_notify_mq_uv);
 	}
 
-	put_online_cpus();
+	cpus_read_unlock();
 	return 0;
 }