ARM: EXYNOS: Make combiner_of_init function static

Silences the following warning:
arch/arm/mach-exynos/common.c:576:12: warning:
symbol 'combiner_of_init' was not declared. Should it be static?
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-exynos/common.c

@@ -573,7 +573,8 @@ static void __init combiner_init(void __iomem *combiner_base,
 }
 
 #ifdef CONFIG_OF
-int __init combiner_of_init(struct device_node *np, struct device_node *parent)
+static int __init combiner_of_init(struct device_node *np,
+				   struct device_node *parent)
 {
 	void __iomem *combiner_base;