drm/rcar-du: Add support for multiple groups

The R8A7790 DU has 3 CRTCs, split in two groups. Support them.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
index 072e28e..160e5eb 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
+++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
@@ -31,9 +31,11 @@
 /*
  * struct rcar_du_device_info - DU model-specific information
  * @features: device features (RCAR_DU_FEATURE_*)
+ * @num_crtcs: total number of CRTCs
  */
 struct rcar_du_device_info {
 	unsigned int features;
+	unsigned int num_crtcs;
 };
 
 struct rcar_du_device {
@@ -45,10 +47,10 @@
 
 	struct drm_device *ddev;
 
-	struct rcar_du_crtc crtcs[2];
+	struct rcar_du_crtc crtcs[3];
 	unsigned int num_crtcs;
 
-	struct rcar_du_group group;
+	struct rcar_du_group groups[2];
 };
 
 static inline bool rcar_du_has(struct rcar_du_device *rcdu,