tty: serial: fix typo "SERIAL_S3C2412"

The Kconfig symbol SERIAL_S3C2412 got removed in commit
da121506 ("serial: samsung: merge
probe() function from all SoC specific extensions"). But it also added a
last reference to that symbol. The commit and the tree make clear that
CPU_S3C2412 should have been used instead.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/Kconfig

@@ -211,7 +211,7 @@ config SERIAL_SAMSUNG
 config SERIAL_SAMSUNG_UARTS_4
 	bool
 	depends on PLAT_SAMSUNG
-	default y if !(CPU_S3C2410 || SERIAL_S3C2412 || CPU_S3C2440 || CPU_S3C2442)
+	default y if !(CPU_S3C2410 || CPU_S3C2412 || CPU_S3C2440 || CPU_S3C2442)
 	help
 	  Internal node for the common case of 4 Samsung compatible UARTs