ACPI: processor: move device _HID into driver

The ACPI0007 _HID used for processor "Device" objects in the namespace
is not needed outside the processor driver, so move it there.  Also, the
#define is only used once, so just remove it and hard-code "ACPI0007".

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>