eventcomm: Fix initialization code
eventcomm: Fix initialization code

num_mt_axes contains the number of non-x/y multitouch axes, and the valuator
mask needs to contains x, y, followed by two empy values for the scroll
valuators, followed by the remaining MT axes.

https://bugs.freedesktop.org/show_bug.cgi?id=45663

Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>

mad-s/xf86-input-synaptics-absolute,mad-s/xf86-input-synaptics-absolute