[ARM] 3784/1: S3C2413: fix config for MACH_S3C2413/MACH_SMDK2413

Patch from Ben Dooks

These two machines are identical, and supported
by the SMDK2413 configuration. When MACH_SMDK2413
is selected, we must also select MACH_S3C2413
to allow machine_is_smdk2413() or machine_is_s3c2413()
to work.

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