ARM: SAMSUNG: Ensure struct sys_device is declared in plat/pm.h

Previously we were relying on it being pulled in by other headers for
the prototype of s3c24xx_irq_suspend() and s3c24xx_irq_resume().
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/plat-samsung/include/plat/pm.h

@@ -17,6 +17,8 @@
 
 #include <linux/irq.h>
 
+struct sys_device;
+
 #ifdef CONFIG_PM
 
 extern __init int s3c_pm_init(void);