ARM: SAMSUNG: Add the missed s3c_gpio_getpull() API

This patch adds the s3c_gpio_getpull() API that has been missed in the
plat-samsung/gpio-config.c and actullay there is its extern declaration
in plat/gpio-cfg.h.

Signed-off-by: Daein Moon <moon9124@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>