Input: appletouch - add Geyser IV support

The new Core2 Duo MacBook Pro has a new keyboard+trackpad named
"Geyser IV".

According to the Info.plist in the OS X kext, it looks like the Geyser
IV trackpad is identical to the Geyser III trackpad: same IOClass
(AppleUSBGrIIITrackpad), same acceleration tables.

Signed-off-by: Julien BLACHE <jb@jblache.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>