ARM: S3C64XX: Fix build for implicit serial_s3c.h inclusion

Some very recent change appears to have removed an implicit inclusion of
serial_s3c.h causing build failures due to references to UART registers
in the serial port restore code in next-20140318.  Include it explicitly
to fix the build.
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-s3c64xx/include/mach/pm-core.h

@@ -15,6 +15,8 @@
 #ifndef __MACH_S3C64XX_PM_CORE_H
 #define __MACH_S3C64XX_PM_CORE_H __FILE__
 
+#include <linux/serial_s3c.h>
+
 #include <mach/regs-gpio.h>
 
 static inline void s3c_pm_debug_init_uart(void)