Move the register and GPIO definition files from plat-s3c64xx into the
machine include direcotry as they are unlikely to be reused outside
mach-s3c64xx.

This move includes removing the empty <mach/regs-clock.h> and replacing
it with the <plat/regs-clock.h> implementation.
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Add the address definitions for S3C64XX_AHB_CONx and
SPCON registers for use in the PM code.
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Add apropriate enable call for clk_48m.
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Add the initial header files for the S3C64XX support to satisfy the
minimal requirements to build a kernel. Some definitions will therefore
be placeholders or empty functions that will ensure that the system can
build and have base functionality. These will be filled in at a later
date.
Signed-off-by: NBen Dooks <ben-linux@fluff.org>