ARM: S5PV210: Fix build warning

Fixed the following warning for S5PV210.

arch/arm/mach-s5pv210/pm.c: In function 's5pv210_pm_add':
arch/arm/mach-s5pv210/pm.c:139: warning: assignment from
incompatible pointer type

Also, staticized the function.
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-s5pv210/pm.c

@@ -88,7 +88,7 @@ static struct sleep_save s5pv210_core_save[] = {
 	SAVE_ITEM(S3C2410_TCNTO(0)),
 };
 
-void s5pv210_cpu_suspend(unsigned long arg)
+static int s5pv210_cpu_suspend(unsigned long arg)
 {
 	unsigned long tmp;