dt-bindings: input: touchscreen: Add compatible for Goodix GT7986U chip

Add a compatible for Goodix touch screen chip GT7986U which is
is expected to be fully compatible with a driver written for GT7375P.

Signed-off-by: Sheng-Liang Pan <sheng-liang.pan@quanta.corp-partner.google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221006185333.v7.3.I52e4b4b20e2eb0ae20f2a9bb198aa6410f04cf16@changeid


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