input: keypad: ep93xx: add DT support for Cirrus EP93xx

input: keypad: ep93xx: add DT support for Cirrus EP93xx

- drop flags, they were not used anyway
- add OF ID match table
- process "autorepeat", "debounce-delay-ms", prescale from device tree
- drop platform data usage and it's header
- keymap goes from device tree now on

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>