Apple touchpads don't use ABS_MT_PRESSURE but they are multitouch touchpads,
so the current pressure-based handling code doesn't apply because it expects
slot-based pressure for mt touchpads.

Apple does however send useful data for ABS_MT_WIDTH_MAJOR/MINOR, so let's use
that instead. The data provided in those is more-or-less random, so we need a
hwdb entry to track the acceptable thresholds.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>