A number of machines that need s3c_device_nand present do not select
this in their Kconfig entries. Add the necessary selection of the
configuration S3C_DEV_NAND so that we avoid the following error:

arch/arm/mach-s3c2410/built-in.o: In function `bast_map_io':
arch/arm/mach-s3c2410/mach-bast.c:634: undefined reference to `s3c_device_nand'
arch/arm/mach-s3c2412/built-in.o: In function `s3c2412_init_uarts':
arch/arm/mach-s3c2412/s3c2412.c:109: undefined reference to `s3c_device_nand'
arch/arm/mach-s3c2412/built-in.o: In function `jive_machine_init':
arch/arm/mach-s3c2412/mach-jive.c:673: undefined reference to `s3c_device_nand'
Signed-off-by: Ben Dooks <ben-linux@fluff.org>