platform/x86: silead_dmi: Fix GP-electronic T701 entry

The GP-electronic T701 has its LCD panel mounted upside-down, initially
my plan was to fix this by transparently rotating the image in the i915
driver (my "drm/i915: Deal with upside-down mounted LCD" patch), but
that approach has been rejected instead the kernel will now export
a "panel orientation" property on the drm-connector for the panel and
let userspace deal with it.

But userspace expects the touchscreen coordinates to match the panel
coordinates *before* applying any rotation, so now that we no longer hide
the upside-down-ness of the LCD panel from userspace the coordinates being
generated are wrong and we need to apply a rotation of 180 degrees to the
coordinates to fix this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>