ARM: EXYNOS: Add support for rtc wakeup

Set the gic arch extension callback to support rtc wakeup.
Signed-off-by: NInderpal Singh <inderpal.singh@linaro.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-exynos/common.c

@@ -463,6 +463,8 @@ void __init exynos4_init_irq(void)
 	 * uses GIC instead of VIC.
 	 */
 	s5p_init_irq(NULL, 0);
+
+	gic_arch_extn.irq_set_wake = s3c_irq_wake;
 }
 
 void __init exynos5_init_irq(void)