mfd: lpc_ich: Convert gpio_version to be enum

We have an anonymous enum for the GPIO versions. Make it named
and use this type for the gpio_version member of struct lpc_ich_info.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230926190834.932233-2-andriy.shevchenko@linux.intel.com


Signed-off-by: Lee Jones <lee@kernel.org>