gpio: rockchip: explan the format of the GPIO version ID

Remove redundant comments and provide a detailed explanation of the
GPIO version ID.

Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20241112015408.3139996-2-ye.zhang@rock-chips.com


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