Synaptics uses anisotropic coordinate system.  On some wide touchpads
vertical resolution can be twice as high as horizontal which causes
unequal sensitivity on x/y directions.  Add support for reading the
resolution with EVIOCGABS ioctl.
Signed-off-by: NTero Saarni <tero.saarni@gmail.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>