dix: Do not allow device transform to be set on valuatorless devices

If a device does not have any valuators, it makes no sense to set the
device transformation. Return a BadMatch error to let the caller know
that they're trying something stupid.

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

dix/devices.c

@@ -177,6 +177,9 @@ DeviceSetProperty(DeviceIntPtr dev, Atom property, XIPropertyValuePtr prop,
             if (!isfinite(f[i]))
                 return BadValue;
 
+	if (!dev->valuator)
+		return BadMatch;
+
         if (!checkonly)
             DeviceSetTransform(dev, f);
     }