drm/ci: Enable CONFIG_BACKLIGHT_CLASS_DEVICE

Dependency for CONFIG_DRM_PANEL_EDP.  Missing this was causing the drm
driver to not probe on devices that use panel-edp.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Tested-by: Helen Koike <helen.koike@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
Link: https://lore.kernel.org/r/20231002164715.157298-1-robdclark@gmail.comSigned-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/ci/arm.config

@@ -24,6 +24,7 @@ CONFIG_DRM_LIMA=y
 CONFIG_DRM_PANEL_SIMPLE=y
 CONFIG_PWM_CROS_EC=y
 CONFIG_BACKLIGHT_PWM=y
+CONFIG_BACKLIGHT_CLASS_DEVICE=y
 
 CONFIG_ROCKCHIP_CDN_DP=n
 

drivers/gpu/drm/ci/arm64.config

@@ -26,6 +26,7 @@ CONFIG_DRM_ETNAVIV=y
 CONFIG_DRM_I2C_ADV7511=y
 CONFIG_PWM_CROS_EC=y
 CONFIG_BACKLIGHT_PWM=y
+CONFIG_BACKLIGHT_CLASS_DEVICE=y
 
 CONFIG_ROCKCHIP_CDN_DP=n