ARM: S3C24XX: Convert SMDK board file to the gpiolib API

Replace SoC specific GPIO functions with the gpiolib API. The LED
gpios are freed right after they are initially configured so they
can be acquired in the s3c24xx_led driver.

This change is required for converting the s3c24xx_led driver
to the gpiolib API.

Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>