ACPI: thinkpad-acpi: react to Lenovo ThinkPad differences in hot key

Lenovo ThinkPads have a slightly different key map layout from IBM
ThinkPads (fn+f2 and fn+f3 are swapped).  Knowing which one we are dealing
with, we can properly set a few more hot keys up by default.

Also, export the correct vendor in the input device, as that information
might be useful to userspace.

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