Patch from Ben Dooks

This is an old definition, and is no longer used anywhere.
Add a comment to that effect in the header file
include/asm-arm/arch-s3c2410/timex.h and remove all other
references.

Thanks to Klaus Fetscher for pointing out that it isn't
used anymore

Signed-off-by: Ben Dooks
Signed-off-by: Russell King