gpio: pca9570: fix kerneldoc

gpio: pca9570: fix kerneldoc

While renaming one of the fields in the driver data struct, the kerneldoc
was not updated which apparently angers the test robot now.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308171538.nKKUOtbg-lkp@intel.com/
Fixes: a3f7c1d6ddcb ("gpio: pca9570: rename platform_data to chip_data")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>