dix: support the transformation matrix for relative devices.

dix: support the transformation matrix for relative devices.

The transformation matrix we previously stored was a scaled matrix based on
the axis ranges of the device. For relative movements, the scaling is not
required (or desired).

Store two separate matrices, one as requested by the client, one as the
product of [scale . matrix . inv_scale]. Depending on the type of movement,
apply the respective matrix.

For relative movements, also drop the translation component since it doesn't
really make sense to use that bit.

Input ABI 19

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>