ARM: Samsung: Make uart_save static in pm.c file

Fixes the following sparse warning:
arch/arm/plat-samsung/pm.c:77:21:
warning: symbol 'uart_save' was not declared. Should it be static?
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/plat-samsung/pm.c

@@ -74,7 +74,7 @@ unsigned char pm_uart_udivslot;
 
 #ifdef CONFIG_SAMSUNG_PM_DEBUG
 
-struct pm_uart_save uart_save[CONFIG_SERIAL_SAMSUNG_UARTS];
+static struct pm_uart_save uart_save[CONFIG_SERIAL_SAMSUNG_UARTS];
 
 static void s3c_pm_save_uart(unsigned int uart, struct pm_uart_save *save)
 {