Input: Add driver for Cypress Generation 5 touchscreen

This is the basic driver for the Cypress TrueTouch Gen5 touchscreen
controllers. This driver supports only the I2C bus but it uses regmap
so SPI support could be added later.
The touchscreen can retrieve some defined zone that are handled as
buttons (according to the hardware). That is why it handles
button and multitouch events.

Reviewed-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
Signed-off-by: Alistair Francis <alistair@alistair23.me>
Tested-by: Andreas Kemnade <andreas@kemnade.info> # Kobo Clara HD
Tested-by: Peter Geis <pgwipeout@gmail.com>
Link: https://lore.kernel.org/r/20221026114908.191472-2-alistair@alistair23.me


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