Input: xen-kbdfront - do not advertise multi-touch pressure support

Some user-space applications expect multi-touch pressure
on contact to be reported if it is advertised in device
properties. Otherwise, such applications may treat reports
not as actual touches, but hovering. Currently this is
only advertised, but not reported.
Fix this by not advertising that ABS_MT_PRESSURE is supported.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Andrii Chepurnyi <andrii_chepurnyi@epam.com>
Patchwork-Id: 10140017
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>