Input: ALPS - add support for touchpads with 4-directional button
Input: ALPS - add support for touchpads with 4-directional button

The touchpad on Acer Aspire 5720, 5520 and some other Aspire models
(signature 0x73, 0x02, 0x50) has a button that can be rocked in 4
different directions. Make the driver to generate BTN_0..BTN_3 events
in response. The Synaptics driver by default maps BTN_0 and BTN_1 to
up and down, so there should be no visible changes with the old setup
that generated BTN_FORWARD and BTN_BACK (also mapped to up and down).

Signed-off-by: Maxim Levitsky <987dc8b9c8aa842b87027603482f1f602de1ce0a@gmail.com>
Signed-off-by: Dmitry Torokhov <10a8c465cefc9bdd6c925e26964d23c90f1141cc@mail.ru>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs