eventcomm: drop some use of mtdev
eventcomm: drop some use of mtdev

When checking the device don't open a new mtdev instance, use the existing
libevdev struct.

Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>
Reviewed-by: Hans de Goede <9fa1be1a5b5729e4c6b404f34c9ce49ff4882fd8@redhat.com>
Reviewed-by: Benjamin Tissoires <7a0e50e3f6a0939db82b6a8a423c08a163896f41@gmail.com>

eyko/xf86-input-synaptics,jiixyj/xf86-input-synaptics,quadpixels/three-finger-dragging,jiixyj/xf86-input-synaptics,eyko/xf86-input-synaptics,gdestuynder/xf86-input-synaptics,mortehu/xf86-input-synaptics,quadpixels/three-finger-dragging,nanderson94/xf86-input-synaptics,RsrchBoy/xserver-xorg-input-synaptics,nanderson94/xf86-input-synaptics,mortehu/xf86-input-synaptics,sencer/synaptics,RsrchBoy/xserver-xorg-input-synaptics,sencer/synaptics,gdestuynder/xf86-input-synaptics