Input: i8042 - add a PNP entry to the aux device list

Windows checks for an ALPS PS/2 device in PNP. Add it on the off-chance
that there's a machine that expresses this without also providing a
compatibility ID.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>