[ARM] 4015/1: s3c2410 cpu ifdefs

The patch adds ifdefs around per cpu definitions. Otherwise, if
not all cpu types are selected, the kernel does not link.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>