drm/rockchip: Fix Kconfig dependencies for display-port encoders

The DP-helper module has been replaced by the display-helper module.
So the driver have to select it.
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 1e0f6642("drm/display: Introduce a DRM display-helper module")
Signed-off-by: Ren Zhijie <renzhijie2@huawei.com>
Reviewed-by: Andy Yan <andy.yan@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220507100910.93705-1-renzhijie2@huawei.com

drivers/gpu/drm/rockchip/Kconfig

@@ -2,7 +2,6 @@
 config DRM_ROCKCHIP
 	tristate "DRM Support for Rockchip"
 	depends on DRM && ROCKCHIP_IOMMU
-	select DRM_DISPLAY_HELPER if ROCKCHIP_ANALOGIX_DP
 	select DRM_GEM_CMA_HELPER
 	select DRM_KMS_HELPER
 	select DRM_PANEL
@@ -38,6 +37,7 @@ config ROCKCHIP_VOP2
 config ROCKCHIP_ANALOGIX_DP
 	bool "Rockchip specific extensions for Analogix DP driver"
 	depends on ROCKCHIP_VOP
+	select DRM_DISPLAY_HELPER
 	select DRM_DISPLAY_DP_HELPER
 	help
 	  This selects support for Rockchip SoC specific extensions
@@ -47,6 +47,8 @@ config ROCKCHIP_ANALOGIX_DP
 config ROCKCHIP_CDN_DP
 	bool "Rockchip cdn DP"
 	depends on EXTCON=y || (EXTCON=m && DRM_ROCKCHIP=m)
+	select DRM_DISPLAY_HELPER
+	select DRM_DISPLAY_DP_HELPER
 	help
 	  This selects support for Rockchip SoC specific extensions
 	  for the cdn DP driver. If you want to enable Dp on