input: remove davinci keyboard driver

The dm365evm board was removed, and no other users of this
device exist.

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>