ARM: S3C64XX: Move core support to mach-s3c64xx

Move the core S3C64XX support to mach-s3c64xx as it is unlikely to be used
outside of this directory. Also move the SoC header files in with it.

This includes the clock, cpu, cpufreq, dma, gpiolib and pll support.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>