[ARM] 4511/1: S3C: updated LLSERIAL Kconfig defines for CPU support

Update the Kconfig to create configuration options based on which
CPUs are supported for the low level serial code. This means that
the debug macros can be optimised for the type(s) of CPU that are
being used.

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