ASoC: Fix S3C64xx IIS driver for Samsung header reorg

The reorgs of the Samsung headers have moved the GPIO bank definitions
from plat/ to mach/ - the IIS driver needs to be updated to take care
of this.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>