[PATCH] USB: MacBook Pro touchpad support

Add support for MacBook touchpad in appletouch driver.
Thanks to Alex Harper for the informations.

Use u16 instead of int16_t in atp_is_geyser* functions.

Acked-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Stelian Pop <stelian@popies.net>
Signed-off-by: Nicolas Boichat <nicolas@boichat.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>