gpio: 104-idi-48: Migrate to gpio-regmap API

The regmap API supports IO port accessors so we can take advantage of
regmap abstractions rather than handling access to the device registers
directly in the driver. Despite the underlying interface being based on
i8255, it is simpler to use the gpio-regmap API directly because the
104-IDI-48 device features only input signals. Therefore, the dependence
on the i8255 GPIO library is removed in this patch.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>