Input: ar1021_i2c - set INPUT_PROP_DIRECT

If INPUT_PROP_DIRECT is set, userspace doesn't have to fall back to old
ways of identifying touchscreen devices. Let's add it.

Signed-off-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>