drm: rcar-du: Enable VSP compositor by default on Gen3

On Gen3 hardware the VSP compositor is required for display. Enable it
by default in the kernel configuration. The option is kept
user-configurable for testing purpose on Gen2 platforms.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

drivers/gpu/drm/rcar-du/Kconfig

@@ -26,7 +26,8 @@ config DRM_RCAR_LVDS
 	  Enable support for the R-Car Display Unit embedded LVDS encoders.
 
 config DRM_RCAR_VSP
-	bool "R-Car DU VSP Compositor Support"
+	bool "R-Car DU VSP Compositor Support" if ARM
+	default y if ARM64
 	depends on DRM_RCAR_DU
 	depends on VIDEO_RENESAS_VSP1=y || (VIDEO_RENESAS_VSP1 && DRM_RCAR_DU=m)
 	help