ASoC: Convert S3C2412 I2S driver to gpiolib API

The s3c2410_gpio* calls are obsolete and have been scheduled for
removal since several kernel releases. Remove them and use common
gpiolib API.
This patch is a prerequisite for removal of the obsolete S3C24XX
SoC GPIO definitions.

Compile tested only.

Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>