Documentation: 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().

Update the documentation accordingly.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210803141621.780504-2-bigeasy@linutronix.de

Documentation/core-api/cpu_hotplug.rst

@@ -220,7 +220,7 @@ goes online (offline) and during initial setup (shutdown) of the driver. However
 each registration and removal function is also available with a ``_nocalls``
 suffix which does not invoke the provided callbacks if the invocation of the
 callbacks is not desired. During the manual setup (or teardown) the functions
-``get_online_cpus()`` and ``put_online_cpus()`` should be used to inhibit CPU
+``cpus_read_lock()`` and ``cpus_read_unlock()`` should be used to inhibit CPU
 hotplug operations.
 
 

Documentation/trace/ftrace.rst

@@ -2762,7 +2762,7 @@ listed in:
   put_prev_task_idle
   kmem_cache_create
   pick_next_task_rt
-  get_online_cpus
+  cpus_read_lock
   pick_next_task_fair
   mutex_lock
   [...]