drm/bridge: ps8640: Return an error for incorrect attach flags

Bridge drivers that implement the new model only shall return an error
from their attach() handler when the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag
is not set. So make sure we return an error because only the new
drm_bridge model is supported.
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Bilal Wasim <bwasim.lkml@gmail.com>
Tested-by: Bilal Wasim <bwasim.lkml@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200826081526.674866-4-enric.balletbo@collabora.com

drivers/gpu/drm/bridge/parade-ps8640.c

@@ -200,6 +200,10 @@ static int ps8640_bridge_attach(struct drm_bridge *bridge,
 						   .channel = 0,
 						   .node = NULL,
 						 };
+
+	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
+		return -EINVAL;
+
 	/* port@0 is ps8640 dsi input port */
 	in_ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
 	if (!in_ep)