Input: edt-ft5x06 - convert to use regmap API

It replaces custom read/write functions with regmap API, making the
driver code more generic.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/r/20230402200951.1032513-8-dario.binacchi@amarulasolutions.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: passgat