[PATCH] drm/bridge: lvds-encoder: Fix build error while CONFIG_DRM_KMS_HELPER=m

[YueHaibing]

If DRM_LVDS_ENCODER=y but CONFIG_DRM_KMS_HELPER=m,
build fails:

drivers/gpu/drm/bridge/lvds-encoder.o: In function `lvds_encoder_probe':
lvds-encoder.c:(.text+0x155): undefined reference to `devm_drm_panel_bridge_add'
drivers/gpu/drm/bridge/tc358764.o:(.rodata+0x228): undefined reference to `drm_atomic_helper_connector_reset'
drivers/gpu/drm/bridge/tc358764.o:(.rodata+0x240): undefined reference to `drm_helper_probe_single_connector_modes'
drivers/gpu/drm/bridge/tc358764.o:(.rodata+0x268): undefined reference to `drm_atomic_helper_connector_duplicate_state'
drivers/gpu/drm/bridge/tc358764.o:(.rodata+0x270): undefined reference to `drm_atomic_helper_connector_destroy_state'

Reported-by: Hulk Robot <hulkci at huawei.com>
Fixes: dbb58bfd9ae6 drm/bridge: ("Fix lvds-encoder since the panel_bridge rework.")
Signed-off-by: YueHaibing <yuehaibing at huawei.com>
---
 drivers/gpu/drm/bridge/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index a6eec90..77e4b95 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -48,6 +48,7 @@ config DRM_DUMB_VGA_DAC
 config DRM_LVDS_ENCODER
 	tristate "Transparent parallel to LVDS encoder support"
 	depends on OF
+	select DRM_KMS_HELPER
 	select DRM_PANEL_BRIDGE
 	help
 	  Support for transparent parallel to LVDS encoders that don't require
-- 
2.7.4