drm: plug memory leak on drm_setup() failure

Currently we fail to free and detach the drm_file when drm_setup() fails.
Use the drm_close_helper to do address that.
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114084410.15266-2-emil.l.velikov@gmail.com

drivers/gpu/drm/drm_file.c

@@ -330,9 +330,11 @@ int drm_open(struct inode *inode, struct file *filp)
 		goto err_undo;
 	if (need_setup) {
 		retcode = drm_setup(dev);
-		if (retcode)
+		if (retcode) {
+			drm_close_helper(filp);
 			goto err_undo;
 		}
+	}
 	return 0;
 
 err_undo: