ARM: at91: at91_dt_defconfig: Enable BACKLIGHT_CLASS_DEVICE

DRM_PANEL_SIMPLE config depends on BACKLIGHT_CLASS_DEVICE, this
avoids de-selecting the panel simple driver and avoids probe failures.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
Acked-by: Dharma Balasubiramani <dharma.b@microchip.com>

Author: manikandan-m11

arch/arm/configs/at91_dt_defconfig

@@ -207,6 +207,7 @@ CONFIG_DRM_MICROCHIP_LVDS_SERIALIZER=y
 CONFIG_FB_ATMEL=y
 CONFIG_BACKLIGHT_ATMEL_LCDC=y
 CONFIG_BACKLIGHT_PWM=y
+CONFIG_BACKLIGHT_CLASS_DEVICE=y
 CONFIG_SOUND=y
 CONFIG_SND=y
 CONFIG_SND_USB_AUDIO=y