touchpad: Route top softbuttons through the trackstick if we've one

touchpad: Route top softbuttons through the trackstick if we've one

The touchpad top softbuttons such as found on the Lenove T440 are intended for
use with the trackstick. Route their events through the trackstick, so that
they can be used for e.g. middle button scrolling with the trackstick.

Note that sending top button events to a disabled trackpoint makes no sense
(and will mess up internal state). Likely a user with a disabled trackpoint
will still expect the top buttons to work, so rather than not sending events
in that case, simply treat a suspendeded trackpoint as not being there, and
send the events directly from the touchpad device.

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