fix how kernel BTN_* maps to GESTURE_BUTTON_*

Recently a regression occurred where the kernel representation of physical
buttons was being incorrectly mapped to GESTURE_BUTTON_* values.

BUG=chromium-os:30812
TEST=capture touchpad log of a physical button press
     inspect resulting log in tpview
     notice "buttonsDown": 1 (GESTURES_BUTTON_LEFT) for all clicks in
       all hardwareState structs.

Change-Id: I3014d6dd9f5bc3ba142bb704ea81f91bde792fc3
3 files changed