Input: psmouse - disable "palm detection" in the focaltech driver

Apparently, the threshold for large contact area seems to be rather low on
some devices, causing the touchpad to frequently freeze during normal
usage. Because we do now know how we are supposed to use the value in
question, this commit just drops the related code completely.

Signed-off-by: Mathias Gottschlag <mgottschlag@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>