serial: samsung: Register cpufreq notifier only on S3C24xx

The Samsung serial driver registered for CPU frequency transitions to
recalculate its clock when ARM clock frequency changes.  This is needed
only on S3C24xx platform so limit the ifdef to respective cpufreq
driver.

On S3C24xx the ratio ratio between frequencies of UART's parent clock
(pclk) and ARM's parent clock (fclk) remains fixed.  Therefore when ARM
clock frequency goes down, the serial is also affected.
Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/samsung.c

@@ -1577,7 +1577,7 @@ static void s3c24xx_serial_resetport(struct uart_port *port,
 }
 
 
-#ifdef CONFIG_CPU_FREQ
+#ifdef CONFIG_ARM_S3C24XX_CPUFREQ
 
 static int s3c24xx_serial_cpufreq_transition(struct notifier_block *nb,
 					     unsigned long val, void *data)

drivers/tty/serial/samsung.h

@@ -102,7 +102,7 @@ struct s3c24xx_uart_port {
 
 	struct s3c24xx_uart_dma		*dma;
 
-#ifdef CONFIG_CPU_FREQ
+#ifdef CONFIG_ARM_S3C24XX_CPUFREQ
 	struct notifier_block		freq_transition;
 #endif
 };