w1: gpio: Don't use platform data for driver data

w1: gpio: Don't use platform data for driver data

struct device's .platform_data isn't for drivers to write to. For
driver-specific data there is .driver_data instead.

As there is no in-tree platform that provides w1_gpio_platform_data,
drop the include file and replace it by a local struct w1_gpio_ddata.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/8f7ebe03ddaa5a5c6e2b36fecdf59da7fc373527.1701727212.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>