Input: cyttsp - remove public header

There is nothing in include/linux/input/cyttsp.h that might be of interes
to the kernel at large, so let's move this information into the driver
code and remove the header.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210531052307.1433979-2-dmitry.torokhov@gmail.com


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