Input: add driver for Hynitron CST816x series

Input: add driver for Hynitron CST816x series

Introduce support for the Hynitron CST816x series touchscreen controller
used for 240×240 1.28-inch Round LCD Display Module manufactured
by Waveshare Electronics. The driver is designed based on an Arduino
implementation marked as under MIT License. This driver is written
for a particular round display based on the CST816S controller, which
is not compatiable with existing driver for Hynitron controllers.

Signed-off-by: Oleh Kuzhylnyi <kuzhylol@gmail.com>
Link: https://lore.kernel.org/r/20250921125939.249788-2-kuzhylol@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>