Input: add driver for Hynitron cstxxx touchscreens

Add support for the Hynitron cst3xx controller found on devices such
as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver
was built from sources provided by Hynitron to Anbernic (possibly
via Rockchip as an intermediary) and marked as GPLv2 in the code.
This driver was written strictly for the cst3xx series, but in
most places was left somewhat generic so support could be easily
added to other devices in the future.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20221028202636.14341-4-macroalpha82@gmail.com


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