Each platform has to add support for CPU hotplugging itself by providing
suitable definitions for the cpu_disable and cpu_die of the smp_ops
methods and setting SYS_SUPPORTS_HOTPLUG_CPU.  A platform should only set
SYS_SUPPORTS_HOTPLUG_CPU once all it's smp_ops definitions have the
necessary changes.  This patch contains the changes to the dummy smp_ops
definition for uni-processor systems.

Parts of the code contributed by Cavium Inc.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Otherwise CPU 0 doesn't show up in sysfs which breaks some software.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>