[ARM] 2855/1: S3C2410 - add CLKSLOW definitions, and show in init

Patch from Ben Dooks

Add the definitions for the S3C2410_CLKSLOW registers to
the header files, and show the values when the system
starts up

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>