[PLEASE TEST] Better support for Synaptics Touchpads

[Marc Fonvieille]

Hello,

I updated my -CURRENT (from 16/08) laptop to today's -CURRENT, and I see
a lot of difference with my touchpad.
Well, it's really not useable, the touchpad is less accurate, the double
tap & hold is not working anymore etc.  To sum up, if I want to use X
with my laptop, I have to plug in a mouse.

So I'd like to back to previous behavior, I tried various psm flags to
make my touchpad seen as a vanilla PS/2 mouse, but nothing works.
Is there a way to switch back?

Marc