cpumask: fix cpu-hotplug documentation
cpumask: fix cpu-hotplug documentation

It refers to an obsolete function.

Signed-off-by: Rusty Russell <df9728c9e5104131c08c7adb03af425394842596@rustcorp.com.au>
Cc: Jonathan Corbet <b2ce64d5587c02f12e367eac59751145a0660c51@lwn.net>
Cc: 720929ea79be81617af4e0222565cf72ea2ee041@vger.kernel.org

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs