linux-wandboard

ACPI: thinkpad-acpi: rename pci HID constant

Rename an internal driver constant, on request by Len Brown.  Also,
document exactly what it is for.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>