gpio: ge: Make driver OF-independent

There is nothing in the driver that requires OF APIs,
make the driver OF independent.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>