Upstream doesn't like this patch.

Instead of SEMI_MT, present a full mt interface with simulated contact
positions for >=3 fingers.  Enables e.g. multi-finger tap and drag for
old userspace applications which only count the contact positions.
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>