S5P: Exynos: Config: Enable GPIO CMD config

Enabling configs for GPIO CMD, EXYNOS4 family and replacing
exynos_gpio_get with new linear GPIO pin number required
because of the new function asking only 2 arguments (pin
and value) instead of 3 (bank, pin and value).

Signed-off-by: Akshay Saraswat <akshay.s@samsung.com>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>