EXYNOS5: Make all display related code dependent on CONFIG_LCD

u-boot compilation fails for smdk5250 when we deselect CONFIG_LCD
from the main config file.

Following error was observed:
drivers/video/libvideo.o: In function `exynos_lcd_init':
/home/ajay/u-boot-samsung/drivers/video/exynos_fb.c:68: undefined reference to `lcd_set_flush_dcache'

This is because exynos video drivers have dependency on CONFIG_LCD.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/board/samsung/smdk5250/smdk5250.c b/board/samsung/smdk5250/smdk5250.c
index 9c4bf9b..7a5f132 100644
--- a/board/samsung/smdk5250/smdk5250.c
+++ b/board/samsung/smdk5250/smdk5250.c
@@ -281,6 +281,7 @@
 }
 #endif
 
+#ifdef CONFIG_LCD
 void cfg_lcd_gpio(void)
 {
 	struct exynos5_gpio_part1 *gpio1 =
@@ -374,3 +375,4 @@
 
 	exynos_set_dp_platform_data(&dp_platform_data);
 }
+#endif