Add ACPI SSDT/DSDT support for CPU hotplug.

Add ACPI SSDT/DSDT support for CPU hotplug.

Move the SSDT defined processors from _PR to _SB namespace.

Extend the dynamically generated SSDT to include per cpu hotplug
methods.  These methods just call methods defined in the DSDT.  Also
dynamically generate a NTFY method and a CPON array of the
online/available CPUs.  Add file src/ssdt-proc.dsl with directions for
generating the per-cpu processor object AML code.

Extend the DSDT to include methods for handling cpu hotplug
notifications and methods for handling cpu status requests originating
from the SSDT methods.