[PATCH] drm: panel: fix s6e3ha2.c build errors

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Fix build errors in panel-samsung-s6e3ha2.c driver build. The driver
uses backlight interfaces so it should depend on BACKLIGHT_CLASS_DEVICE.

drivers/built-in.o: In function `s6e3ha2_remove':
panel-samsung-s6e3ha2.c:(.text+0xe49c2): undefined reference to `backlight_device_unregister'
drivers/built-in.o: In function `s6e3ha2_probe':
panel-samsung-s6e3ha2.c:(.text+0xe4dad): undefined reference to `backlight_device_register'
panel-samsung-s6e3ha2.c:(.text+0xe4e33): undefined reference to `backlight_device_unregister'

Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: Hoegeun Kwon <hoegeun.kwon@xxxxxxxxxxx>
---
 drivers/gpu/drm/panel/Kconfig |    1 +
 1 file changed, 1 insertion(+)

--- lnx-412-rc5.orig/drivers/gpu/drm/panel/Kconfig
+++ lnx-412-rc5/drivers/gpu/drm/panel/Kconfig
@@ -66,6 +66,7 @@ config DRM_PANEL_SAMSUNG_S6E3HA2
 	tristate "Samsung S6E3HA2 DSI video mode panel"
 	depends on OF
 	depends on DRM_MIPI_DSI
+	depends on BACKLIGHT_CLASS_DEVICE
 	select VIDEOMODE_HELPERS
 
 config DRM_PANEL_SAMSUNG_S6E8AA0