gpio: samsung: Fix input mode setting function for GPIO int

This patch makes GPIO pin to INTERRUPT mode or INPUT mode according
to bitmap_gpio_int. When the related bit of bitmap_gpio_int is set,
it makes GPIO pin to INTERRUPT mode instrad of INPUT mode in the
samsung_gpiolib_4bit_input function.

Signed-off-by: Eunki Kim <eunki_kim@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>