tools: coasting speed is not capped at 20, cap it at 255
tools: coasting speed is not capped at 20, cap it at 255

Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>
(cherry picked from commit 0352c67fa2a7224b5a3bf03a934b3c7af42b4f51)

philipn/xserver-xorg-input-synaptics,RsrchBoy/xserver-xorg-input-synaptics,RsrchBoy/xserver-xorg-input-synaptics,philipn/xserver-xorg-input-synaptics,philipn/xserver-xorg-input-synaptics