drm: rcar-du: Fix vblank initialization

The drm_vblank_init() takes the total number of CRTCs as an argument,
but the rcar-du driver passes a bitmask of the CRTC indices. Fix it.

Fixes: 4bf8e19 ("drm: Renesas R-Car Display Unit DRM driver")
Reported-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

drivers/gpu/drm/rcar-du/rcar_du_kms.c

@@ -582,7 +582,7 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 	 * Initialize vertical blanking interrupts handling. Start with vblank
 	 * disabled for all CRTCs.
 	 */
-	ret = drm_vblank_init(dev, (1 << rcdu->num_crtcs) - 1);
+	ret = drm_vblank_init(dev, rcdu->num_crtcs);
 	if (ret < 0)
 		return ret;