drm/mediatek: Only try to attach bridge if there is one

Even if dsi->bridge is NULL, we still try to call drm_bridge_attach,
and print out an error message, before creating the connector.

When no bridge is provided, let's skip these 2 steps and directly
create the connector.

Signed-off-by: Nicolas Boichat <[e-mail]>
Signed-off-by: CK Hu <[e-mail]>
Reviewed-by: Andrzej Hajda <[e-mail]>

drivers/gpu/drm/mediatek/mtk_dsi.c

···
 	dsi->encoder.possible_crtcs = 1;
 
 	/* If there's a bridge, attach to it and let it create the connector */
-	ret = drm_bridge_attach(&dsi->encoder, dsi->bridge, NULL);
-	if (ret) {
-		DRM_ERROR("Failed to attach bridge to drm\n");
-
+	if (dsi->bridge) {
+		ret = drm_bridge_attach(&dsi->encoder, dsi->bridge, NULL);
+		if (ret) {
+			DRM_ERROR("Failed to attach bridge to drm\n");
+			goto err_encoder_cleanup;
+		}
+	} else {
 		/* Otherwise create our own connector and attach to a panel */
 		ret = mtk_dsi_create_connector(drm, dsi);
 		if (ret)