[CPUFREQ/S3C64xx] Move S3C64xx CPUfreq driver into drivers/cpufreq

This is a straight code motion patch, there are no changes to the driver
itself. The Kconfig is left untouched as the ARM CPUfreq Kconfig is all
in one big block in arm/Kconfig and should be moved en masse rather than
being done piecemeal.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Dave Jones <davej@redhat.com>