[ARM] Ensure CONFIG_SERIAL_SAMSUNG_UARTS is always set.

Always set CONFIG_SERIAL_SAMSUNG_UARTS when building any
of the S3C platforms as even if the driver is not selected
there it is still the facility for the machine files to
register configuration data for the possibility of the
driver being built.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>

drivers/serial/Kconfig

@@ -457,7 +457,7 @@ config SERIAL_SAMSUNG
 
 config SERIAL_SAMSUNG_UARTS
 	int
-	depends on SERIAL_SAMSUNG
+	depends on ARM && PLAT_S3C
 	default 2 if ARCH_S3C2400
 	default 4 if ARCH_S3C64XX || CPU_S3C2443
 	default 3