ARM: SAMSUNG: Fix Section mismatch in samsung_bl_set()

WARNING: vmlinux.o(.text+0xf47c): Section mismatch in reference from the function samsung_bl_set() to the (unknown reference) .init.data:(unknown)
The function samsung_bl_set() references
the (unknown reference) __initdata (unknown).
This is often because samsung_bl_set lacks a __initdata
annotation or the annotation of (unknown) is wrong.
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

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

@@ -20,7 +20,7 @@ struct samsung_bl_gpio_info {
 	int func;
 };
 
-extern void samsung_bl_set(struct samsung_bl_gpio_info *gpio_info,
+extern void __init samsung_bl_set(struct samsung_bl_gpio_info *gpio_info,
 	struct platform_pwm_backlight_data *bl_data);
 
 #endif /* __ASM_PLAT_BACKLIGHT_H */