gpio: davinci: use devm_platform_ioremap_resource()

Use the new helper that wraps the calls to platform_get_resource() and
devm_ioremap_resource() together.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>