gpio: pca9570: rename platform_data to chip_data

gpio: pca9570: rename platform_data to chip_data

By convention platform_data refers to structures passed to drivers by
code that registers devices. When talking about model-specific data
structures associated with OF compatibles, we usually call them chip_data.

In order to avoid confusion rename all mentions of platform_data to
chip_data.

Fixes: fbb19fe17eae ("gpio: pca9570: add slg7xl45106 support")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>