[PATCH] ARM: do not mark CPU 0 as hotpluggable

A quick poll of the ARM platforms that implement CPU Hotplug support
shows that every platform treats CPU 0 as a special case that cannot be
hotplugged.  In fact every platform has identical code for
platform_cpu_die which returns -EPERM in the case of CPU 0.

The user-facing sysfs interfaces should reflect this by not populating
an 'online' entry for CPU 0 at all.  This better reflects reality by
making it clear to users that CPU 0 cannot be hotplugged.

This patch prevents CPU 0 from being marked as hotpluggable on all ARM
platforms during CPU registration.  This in turn prevents the creation
of an 'online' sysfs interface for that CPU.

Signed-off-by: Mike Turquette <mturquette at ti.com>
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