ARM: S3C24XX: Convert the touchscreen setup code to common GPIO API

Replace the S3C24XX SoC specific calls with the common gpiolib
API. This removes one more user of an obsolete GPIO API.

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