lustre/fld: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO

This patch fixes coccinelle error regarding usage of IS_ERR and
PTR_ERR instead of PTR_ERR_OR_ZERO.
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/fld/fld_request.c

@@ -504,10 +504,7 @@ static int __init fld_mod_init(void)
 	fld_type_proc_dir = lprocfs_register(LUSTRE_FLD_NAME,
 					     proc_lustre_root,
 					     NULL, NULL);
-	if (IS_ERR(fld_type_proc_dir))
-		return PTR_ERR(fld_type_proc_dir);
-
-	return 0;
+	return PTR_ERR_OR_ZERO(fld_type_proc_dir);
 }
 
 static void __exit fld_mod_exit(void)