xen/processor-passthru: Provide an driver that passes struct acpi_processor data...

xen/processor-passthru: Provide an driver that passes struct acpi_processor data to the hypervisor.

The ACPI processor processes the _Pxx and the _Cx state information
which are populated in the 'struct acpi_processor' per-cpu structure.
We read the contents of that structure and pass it up the Xen hypervisor.

The ACPI processor along with the CPU freq driver does all the heavy-lifting
for us (filtering, calling ACPI functions, etc) so that the contents is correct.
After we are done parsing the information, we wait in case of hotplug CPUs
get loaded and then pass that information to the hypervisor.

[v1-v2: Initial RFC implementations that were posted]
[v3: Changed the name to passthru suggested by Pasi Kärkkäinen <pasik@iki.fi>]
[v4: Added vCPU != pCPU support - aka dom0_max_vcpus support]
[v5: Cleaned up the driver, fix bug under Athlon XP]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Conflicts:

	drivers/xen/Kconfig
	drivers/xen/Makefile