Allwinner: Add canupdate.sh script

projects/Allwinner/bootloader/canupdate.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2023-present Team LibreELEC (https://libreelec.tv)
+
+# Allow upgrades between arm and aarch64
+if [ "${1}" = "@PROJECT@.arm" -o "${1}" = "@PROJECT@.aarch64" ]; then
+  exit 0
+else
+  exit 1
+fi