This simply doesn't work for low-dpi mice. Normalizing a 400dpi mouse to a
1000dpi mouse forces a minimum movement of 2.5 units and the resulting pixel
jumps. It is impossible for the caller to detect whether the jump was caused
by a single motion or multiple motion events.

This is technically an API break, but not really.

The accelerated data was already relatively meaningless, even if normalized as
the data did not correspond predictably to any input motion (unless you know
the implementation acceleration function in the caller). So we can drop the
mention from there without expecting any ill effects in the caller.

The unaccelerated data was useless for low-dpi mice and could only be used to
measure the physical distance of the mouse movement - something not used in
any caller we're aware of (if needed, we can add that functionality as a
separate call). Dropping motion normalization for unaccelerated deltas also
restores true dpi capabilities to users of that API, mostly games that want to
make use of high-dpi mice.

This is a simplified patch, the normalization is still in place for most of
libinput, it merely carries the original coordinates in the event itself.

In the case of touchpads, the coordinates are unnormalized into the x-axis
coordinate space as per the documentation.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>