Input: synaptics - remove TOPBUTTONPAD property for Lenovos 2015

The 2015 series of the Lenovo thinkpads added back the hardware buttons on
top of the touchpad for the trackstick.

Unfortunately, Lenovo used the PNPIDs that are supposed to be "5 buttons"
touchpads, so the new laptops also have the INPUT_PROP_TOPBUTTONPAD. Yay!

Instead of manually removing each of the new ones, or hoping that we know
all the current ones, we can consider that the PNPIDs list that were given
contains touchpads that have the trackstick buttons, either physically
wired to them, or emulated with the top software button property.

Thanks to the extra buttons capability in query $10, we can reliably detect
the physical buttons from the software ones, and so we can remove the
TOPBUTTONPAD property even if it was declared as such.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>