gpio: davinci: drop platform data support

There are no more any board files that use the platform data for
gpio-davinci. We can remove the header defining it and port the code to
no longer store any context in pdata.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240819151705.37258-1-brgl@bgdev.pl


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>