Do not disable xserver constant deceleration support

This has the side effect of allowing a user to select a profile different than "none" (via xinput), which can allow for xserver's internal acceleration options, but it still gives a good default and allows for constant deceleration which is useful for people with some motor disabilities.

Being able to reach very slow pointer motion is important for some disabled people with limited motor abilities. See also this thread on the mailing list for details.