ARM: S5PV210: Use gpio_request_one

By using gpio_request_one it is possible to set the direction
and initial value in one shot. Thus, using gpio_request_one can
make the code simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>